MINOR: stats: introduce stats_dump_one_line() to dump one stats line

This new function dumps the current stats line according to the
specified format (CSV or HTML for now), and returns these functions'
output code, which will serve later to indicate a failure (eg: buffer
full).

This further simplifies the code since all dumpers now just call this
function.
diff --git a/src/dumpstats.c b/src/dumpstats.c
index 6d088ce..64d60b0 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -3897,6 +3897,18 @@
 	return 1;
 }
 
+static int stats_dump_one_line(const struct field *stats, unsigned int flags, struct proxy *px, struct appctx *appctx)
+{
+	int admin;
+
+	admin = (px->cap & PR_CAP_BE) && px->srv && (appctx->ctx.stats.flags & STAT_ADMIN);
+
+	if (appctx->ctx.stats.flags & STAT_FMT_HTML)
+		return stats_dump_fields_html(stats, admin, flags, px);
+	else
+		return stats_dump_fields_csv(&trash, stats);
+}
+
 /* Dumps a frontend's line to the trash for the current proxy <px> and uses
  * the state from stream interface <si>. The caller is responsible for clearing
  * the trash if needed. Returns non-zero if it emits anything, zero otherwise.
@@ -3961,17 +3973,7 @@
 	stats[ST_F_CONN_RATE_MAX] = mkf_u32(FN_MAX, px->fe_counters.cps_max);
 	stats[ST_F_CONN_TOT]      = mkf_u64(FN_COUNTER, px->fe_counters.cum_conn);
 
-	if (appctx->ctx.stats.flags & STAT_FMT_HTML) {
-		int admin;
-
-		admin = (px->cap & PR_CAP_BE) && px->srv && (appctx->ctx.stats.flags & STAT_ADMIN);
-		stats_dump_fields_html(stats, admin, 0, px);
-	}
-	else { /* CSV mode */
-		/* dump everything */
-		stats_dump_fields_csv(&trash, stats);
-	}
-	return 1;
+	return stats_dump_one_line(stats, 0, px, appctx);
 }
 
 /* Dumps a line for listener <l> and proxy <px> to the trash and uses the state
@@ -4031,17 +4033,7 @@
 		}
 	}
 
-	if (appctx->ctx.stats.flags & STAT_FMT_HTML) {
-		int admin;
-
-		admin = (px->cap & PR_CAP_BE) && px->srv && (appctx->ctx.stats.flags & STAT_ADMIN);
-		stats_dump_fields_html(stats, admin, flags, px);
-	}
-	else { /* CSV mode */
-		/* dump everything */
-		stats_dump_fields_csv(&trash, stats);
-	}
-	return 1;
+	return stats_dump_one_line(stats, flags, px, appctx);
 }
 
 enum srv_stats_state {
@@ -4300,17 +4292,7 @@
 			stats[ST_F_COOKIE] = mkf_str(FO_CONFIG|FN_NAME|FS_SERVICE, sv->cookie);
 	}
 
-	if (appctx->ctx.stats.flags & STAT_FMT_HTML) {
-		int admin;
-
-		admin = (px->cap & PR_CAP_BE) && px->srv && (appctx->ctx.stats.flags & STAT_ADMIN);
-		stats_dump_fields_html(stats, admin, flags, px);
-	}
-	else { /* CSV mode */
-		/* dump everything */
-		stats_dump_fields_csv(&trash, stats);
-	}
-	return 1;
+	return stats_dump_one_line(stats, flags, px, appctx);
 }
 
 /* Dumps a line for backend <px> to the trash for and uses the state from stream
@@ -4396,17 +4378,7 @@
 	stats[ST_F_RTIME]        = mkf_u32(FN_AVG, swrate_avg(px->be_counters.d_time, TIME_STATS_SAMPLES));
 	stats[ST_F_TTIME]        = mkf_u32(FN_AVG, swrate_avg(px->be_counters.t_time, TIME_STATS_SAMPLES));
 
-	if (appctx->ctx.stats.flags & STAT_FMT_HTML) {
-		int admin;
-
-		admin = (px->cap & PR_CAP_BE) && px->srv && (appctx->ctx.stats.flags & STAT_ADMIN);
-		stats_dump_fields_html(stats, admin, flags, px);
-	}
-	else { /* CSV mode */
-		/* dump everything */
-		stats_dump_fields_csv(&trash, stats);
-	}
-	return 1;
+	return stats_dump_one_line(stats, flags, px, appctx);
 }
 
 /* Dumps the HTML table header for proxy <px> to the trash for and uses the state from