MINOR: stats: report a distinct output for DOWN caused by agent

Till now we only had "DOWN" on the stats page, whether it's the agent
or regular checks which caused this status. Let's differentiate the
two with "DOWN (agent)" so that admins know that the agent is causing
this status.
diff --git a/src/dumpstats.c b/src/dumpstats.c
index 21eff52..02bff56 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -2819,8 +2819,8 @@
  * from stream interface <si>, stats flags <flags>, and server state <state>.
  * The caller is responsible for clearing the trash if needed. Returns non-zero
  * if it emits anything, zero otherwise. The <state> parameter can take the
- * following values : 0=DOWN, 1=going up, 2=going down, 3=UP, 4,5=NOLB,
- * 6,7=DRAIN, 8=unchecked.
+ * following values : 0=DOWN, 1=DOWN(agent) 2=going up, 3=going down, 4=UP, 5,6=NOLB,
+ * 7,8=DRAIN, 9=unchecked.
  */
 static int stats_dump_sv_stats(struct stream_interface *si, struct proxy *px, int flags, struct server *sv, int state)
 {
@@ -2839,8 +2839,9 @@
 		ref = ref->track;
 
 	if (appctx->ctx.stats.flags & STAT_FMT_HTML) {
-		static char *srv_hlt_st[9] = {
+		static char *srv_hlt_st[10] = {
 			"DOWN",
+			"DOWN (agent)",
 			"DN %d/%d &uarr;",
 			"UP %d/%d &darr;",
 			"UP",
@@ -3058,8 +3059,9 @@
 			chunk_appendf(&trash, "<td class=ac>-</td></tr>\n");
 	}
 	else { /* CSV mode */
-		static char *srv_hlt_st[9] = {
+		static char *srv_hlt_st[10] = {
 			"DOWN,",
+			"DOWN (agent),",
 			"DOWN %d/%d,",
 			"UP %d/%d,",
 			"UP,",
@@ -3660,7 +3662,7 @@
 	case STAT_PX_ST_SV:
 		/* stats.sv has been initialized above */
 		for (; appctx->ctx.stats.sv != NULL; appctx->ctx.stats.sv = sv->next) {
-			int sv_state; /* 0=DOWN, 1=going up, 2=going down, 3=UP, 4,5=NOLB, 6=unchecked */
+			int sv_state;
 
 			if (buffer_almost_full(rep->buf)) {
 				rep->flags |= CF_WAKE_WRITE;
@@ -3683,41 +3685,44 @@
 
 			if (sv->state == SRV_ST_RUNNING || sv->state == SRV_ST_STARTING) {
 				/* server is UP. The possibilities are :
-				 *   - UP, draining, going down    => state = 6
-				 *   - UP, going down              => state = 2
-				 *   - UP, draining                => state = 7
-				 *   - UP, checked                 => state = 3
-				 *   - UP, not checked nor tracked => state = 8
+				 *   - UP, draining, going down    => state = 7
+				 *   - UP, going down              => state = 3
+				 *   - UP, draining                => state = 8
+				 *   - UP, checked                 => state = 4
+				 *   - UP, not checked nor tracked => state = 9
 				 */
 
 				if ((svs->check.state & CHK_ST_ENABLED) &&
 				    (svs->check.health < svs->check.rise + svs->check.fall - 1))
-					sv_state = 2;
-				else
 					sv_state = 3;
+				else
+					sv_state = 4;
 
 				if (server_is_draining(sv))
 					sv_state += 4;
 
-				if (sv_state == 3 && !(svs->check.state & CHK_ST_ENABLED))
-					sv_state = 8; /* unchecked UP */
+				if (sv_state == 4 && !(svs->check.state & CHK_ST_ENABLED))
+					sv_state = 9; /* unchecked UP */
 			}
 			else if (sv->state == SRV_ST_STOPPING) {
 				if ((!(sv->check.state & CHK_ST_ENABLED) && !sv->track) ||
 				    (svs->check.health == svs->check.rise + svs->check.fall - 1))
-					sv_state = 5; /* NOLB */
+					sv_state = 6; /* NOLB */
 				else
-					sv_state = 4; /* NOLB going down */
+					sv_state = 5; /* NOLB going down */
 			}
 			else {	/* stopped */
-				if ((svs->check.state & CHK_ST_ENABLED && !svs->check.health) ||
-				    (svs->agent.state & CHK_ST_ENABLED && !svs->agent.health))
+				if ((svs->agent.state & CHK_ST_ENABLED) && !svs->agent.health)
+					sv_state = 1; /* DOWN (agent) */
+				else if ((svs->check.state & CHK_ST_ENABLED) && !svs->check.health)
 					sv_state = 0; /* DOWN */
+				else if ((svs->agent.state & CHK_ST_ENABLED) || (svs->check.state & CHK_ST_ENABLED))
+					sv_state = 2; /* going up */
 				else
-					sv_state = 1; /* going up */
+					sv_state = 0; /* DOWN, unchecked */
 			}
 
-			if (((sv_state == 0) || (sv->admin & SRV_ADMF_MAINT)) && (appctx->ctx.stats.flags & STAT_HIDE_DOWN)) {
+			if (((sv_state <= 1) || (sv->admin & SRV_ADMF_MAINT)) && (appctx->ctx.stats.flags & STAT_HIDE_DOWN)) {
 				/* do not report servers which are DOWN */
 				appctx->ctx.stats.sv = sv->next;
 				continue;
@@ -3817,23 +3822,25 @@
 	              ".socket	{background: #d0d0d0;}\n"
 	              ".backend	{background: #e8e8d0;}\n"
 	              ".active0	{background: #ff9090;}\n"
-	              ".active1	{background: #ffd020;}\n"
-	              ".active2	{background: #ffffa0;}\n"
-	              ".active3	{background: #c0ffc0;}\n"
-	              ".active4	{background: #ffffa0;}\n"  /* NOLB state shows same as going down */
-	              ".active5	{background: #20a0ff;}\n"  /* NOLB state shows different to be detected */
-	              ".active6	{background: #ffffa0;}\n"  /* DRAIN going down = same as going down */
-	              ".active7	{background: #20a0FF;}\n"  /* DRAIN must be detected (weight=0) */
-	              ".active8	{background: #e0e0e0;}\n"
+	              ".active1	{background: #ff9090;}\n"
+	              ".active2	{background: #ffd020;}\n"
+	              ".active3	{background: #ffffa0;}\n"
+	              ".active4	{background: #c0ffc0;}\n"
+	              ".active5	{background: #ffffa0;}\n"  /* NOLB state shows same as going down */
+	              ".active6	{background: #20a0ff;}\n"  /* NOLB state shows different to be detected */
+	              ".active7	{background: #ffffa0;}\n"  /* DRAIN going down = same as going down */
+	              ".active8 {background: #20a0FF;}\n"  /* DRAIN must be detected (weight=0) */
+	              ".active9	{background: #e0e0e0;}\n"
 	              ".backup0	{background: #ff9090;}\n"
-	              ".backup1	{background: #ff80ff;}\n"
-	              ".backup2	{background: #c060ff;}\n"
-	              ".backup3	{background: #b0d0ff;}\n"
-	              ".backup4	{background: #c060ff;}\n"  /* NOLB state shows same as going down */
-	              ".backup5	{background: #90b0e0;}\n"  /* NOLB state shows same as going down */
-	              ".backup6	{background: #c060ff;}\n"
-	              ".backup7	{background: #cc9900;}\n"
-	              ".backup8	{background: #e0e0e0;}\n"
+	              ".backup1	{background: #ff9090;}\n"
+	              ".backup2	{background: #ff80ff;}\n"
+	              ".backup3	{background: #c060ff;}\n"
+	              ".backup4	{background: #b0d0ff;}\n"
+	              ".backup5	{background: #c060ff;}\n"  /* NOLB state shows same as going down */
+	              ".backup6	{background: #90b0e0;}\n"  /* NOLB state shows same as going down */
+	              ".backup7	{background: #c060ff;}\n"
+	              ".backup8	{background: #cc9900;}\n"
+	              ".backup9	{background: #e0e0e0;}\n"
 	              ".maintain	{background: #c07820;}\n"
 	              ".rls      {letter-spacing: 0.2em; margin-right: 1px;}\n" /* right letter spacing (used for grouping digits) */
 	              "\n"
@@ -3909,21 +3916,21 @@
 	              "Running tasks: %d/%d; idle = %d %%<br>\n"
 	              "</td><td align=\"center\" nowrap>\n"
 	              "<table class=\"lgd\"><tr>\n"
-	              "<td class=\"active3\">&nbsp;</td><td class=\"noborder\">active UP </td>"
-	              "<td class=\"backup3\">&nbsp;</td><td class=\"noborder\">backup UP </td>"
+	              "<td class=\"active4\">&nbsp;</td><td class=\"noborder\">active UP </td>"
+	              "<td class=\"backup4\">&nbsp;</td><td class=\"noborder\">backup UP </td>"
 	              "</tr><tr>\n"
-	              "<td class=\"active2\"></td><td class=\"noborder\">active UP, going down </td>"
-	              "<td class=\"backup2\"></td><td class=\"noborder\">backup UP, going down </td>"
+	              "<td class=\"active3\"></td><td class=\"noborder\">active UP, going down </td>"
+	              "<td class=\"backup3\"></td><td class=\"noborder\">backup UP, going down </td>"
 	              "</tr><tr>\n"
-	              "<td class=\"active1\"></td><td class=\"noborder\">active DOWN, going up </td>"
-	              "<td class=\"backup1\"></td><td class=\"noborder\">backup DOWN, going up </td>"
+	              "<td class=\"active2\"></td><td class=\"noborder\">active DOWN, going up </td>"
+	              "<td class=\"backup2\"></td><td class=\"noborder\">backup DOWN, going up </td>"
 	              "</tr><tr>\n"
 	              "<td class=\"active0\"></td><td class=\"noborder\">active or backup DOWN &nbsp;</td>"
-	              "<td class=\"active8\"></td><td class=\"noborder\">not checked </td>"
+	              "<td class=\"active9\"></td><td class=\"noborder\">not checked </td>"
 	              "</tr><tr>\n"
 	              "<td class=\"maintain\"></td><td class=\"noborder\" colspan=\"3\">active or backup DOWN for maintenance (MAINT) &nbsp;</td>"
 	              "</tr><tr>\n"
-	              "<td class=\"active7\"></td><td class=\"noborder\" colspan=\"3\">active or backup SOFT STOPPED for maintenance &nbsp;</td>"
+	              "<td class=\"active8\"></td><td class=\"noborder\" colspan=\"3\">active or backup SOFT STOPPED for maintenance &nbsp;</td>"
 	              "</tr></table>\n"
 	              "Note: \"NOLB\"/\"DRAIN\" = UP with load-balancing disabled."
 	              "</td>"
@@ -4028,7 +4035,7 @@
 		switch (appctx->ctx.stats.st_code) {
 		case STAT_STATUS_DONE:
 			chunk_appendf(&trash,
-			              "<p><div class=active3>"
+			              "<p><div class=active4>"
 			              "<a class=lfsb href=\"%s%s%s%s\" title=\"Remove this message\">[X]</a> "
 			              "Action processed successfully."
 			              "</div>\n", uri->uri_prefix,
@@ -4038,7 +4045,7 @@
 			break;
 		case STAT_STATUS_NONE:
 			chunk_appendf(&trash,
-			              "<p><div class=active2>"
+			              "<p><div class=active3>"
 			              "<a class=lfsb href=\"%s%s%s%s\" title=\"Remove this message\">[X]</a> "
 			              "Nothing has changed."
 			              "</div>\n", uri->uri_prefix,
@@ -4048,7 +4055,7 @@
 			break;
 		case STAT_STATUS_PART:
 			chunk_appendf(&trash,
-			              "<p><div class=active2>"
+			              "<p><div class=active3>"
 			              "<a class=lfsb href=\"%s%s%s%s\" title=\"Remove this message\">[X]</a> "
 			              "Action partially processed.<br>"
 			              "Some server names are probably unknown or ambiguous (duplicated names in the backend)."
@@ -4095,7 +4102,7 @@
 			break;
 		default:
 			chunk_appendf(&trash,
-			              "<p><div class=active8>"
+			              "<p><div class=active9>"
 			              "<a class=lfsb href=\"%s%s%s%s\" title=\"Remove this message\">[X]</a> "
 			              "Unexpected result."
 			              "</div>\n", uri->uri_prefix,