BUILD: threads: fix minor build warnings when threads are disabled

These potential null-deref warnings are emitted on gcc 7 and above
when threads are disabled due to the use of objt_server() after an
existing validity test. Let's switch to __objt_server() since we
know the pointer is valid, it will not confuse the compiler.

Some of these may be backported to 1.8.
diff --git a/src/cli.c b/src/cli.c
index b99270d..0fbb6f3 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -2043,10 +2043,10 @@
 		if (objt_server(s->target)) {
 			if (s->flags & SF_CURR_SESS) {
 				s->flags &= ~SF_CURR_SESS;
-				HA_ATOMIC_SUB(&objt_server(s->target)->cur_sess, 1);
+				HA_ATOMIC_SUB(&__objt_server(s->target)->cur_sess, 1);
 			}
-			if (may_dequeue_tasks(objt_server(s->target), be))
-				process_srv_queue(objt_server(s->target));
+			if (may_dequeue_tasks(__objt_server(s->target), be))
+				process_srv_queue(__objt_server(s->target));
 		}
 
 		s->target = NULL;
diff --git a/src/proto_http.c b/src/proto_http.c
index 0f8bc22..e2f3009 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -3828,7 +3828,7 @@
 	if (objt_server(s->target)) {
 		if (s->flags & SF_CURR_SESS) {
 			s->flags &= ~SF_CURR_SESS;
-			HA_ATOMIC_SUB(&objt_server(s->target)->cur_sess, 1);
+			HA_ATOMIC_SUB(&__objt_server(s->target)->cur_sess, 1);
 		}
 		if (may_dequeue_tasks(objt_server(s->target), be))
 			process_srv_queue(objt_server(s->target));
@@ -4650,8 +4650,8 @@
 
 			HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 			if (objt_server(s->target)) {
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-				health_adjust(objt_server(s->target), HANA_STATUS_HTTP_HDRRSP);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+				health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_HDRRSP);
 			}
 		abort_response:
 			channel_auto_close(rep);
@@ -4685,8 +4685,8 @@
 
 			HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 			if (objt_server(s->target)) {
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-				health_adjust(objt_server(s->target), HANA_STATUS_HTTP_READ_ERROR);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+				health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_READ_ERROR);
 			}
 
 			channel_auto_close(rep);
@@ -4721,8 +4721,8 @@
 
 			HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 			if (objt_server(s->target)) {
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-				health_adjust(objt_server(s->target), HANA_STATUS_HTTP_READ_TIMEOUT);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+				health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_READ_TIMEOUT);
 			}
 
 			channel_auto_close(rep);
@@ -4771,8 +4771,8 @@
 
 			HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 			if (objt_server(s->target)) {
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-				health_adjust(objt_server(s->target), HANA_STATUS_HTTP_BROKEN_PIPE);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+				health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_BROKEN_PIPE);
 			}
 
 			channel_auto_close(rep);
@@ -4878,9 +4878,9 @@
 	 */
 	if (objt_server(s->target)) {
 		if (txn->status >= 100 && (txn->status < 500 || txn->status == 501 || txn->status == 505))
-			health_adjust(objt_server(s->target), HANA_STATUS_HTTP_OK);
+			health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_OK);
 		else
-			health_adjust(objt_server(s->target), HANA_STATUS_HTTP_STS);
+			health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_STS);
 	}
 
 	/*
@@ -5271,8 +5271,8 @@
 			if (apply_filters_to_response(s, rep, rule_set) < 0) {
 			return_bad_resp:
 				if (objt_server(s->target)) {
-					HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-					health_adjust(objt_server(s->target), HANA_STATUS_HTTP_RSP);
+					HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+					health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_RSP);
 				}
 				HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 			return_srv_prx_502:
@@ -5687,7 +5687,7 @@
 	res->analysers   &= AN_RES_FLT_END;
 	s->req.analysers &= AN_REQ_FLT_END; /* we're in data phase, we want to abort both directions */
 	if (objt_server(s->target))
-		health_adjust(objt_server(s->target), HANA_STATUS_HTTP_HDRRSP);
+		health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_HDRRSP);
 
 	if (!(s->flags & SF_ERR_MASK))
 		s->flags |= SF_ERR_PRXCOND;
diff --git a/src/proto_htx.c b/src/proto_htx.c
index 975fd77..b6c127e 100644
--- a/src/proto_htx.c
+++ b/src/proto_htx.c
@@ -1478,8 +1478,8 @@
 
 			HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 			if (objt_server(s->target)) {
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-				health_adjust(objt_server(s->target), HANA_STATUS_HTTP_READ_ERROR);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+				health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_READ_ERROR);
 			}
 
 			rep->analysers &= AN_RES_FLT_END;
@@ -1509,8 +1509,8 @@
 		else if (rep->flags & CF_READ_TIMEOUT) {
 			HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 			if (objt_server(s->target)) {
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-				health_adjust(objt_server(s->target), HANA_STATUS_HTTP_READ_TIMEOUT);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+				health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_READ_TIMEOUT);
 			}
 
 			rep->analysers &= AN_RES_FLT_END;
@@ -1530,7 +1530,7 @@
 			HA_ATOMIC_ADD(&sess->fe->fe_counters.cli_aborts, 1);
 			HA_ATOMIC_ADD(&s->be->be_counters.cli_aborts, 1);
 			if (objt_server(s->target))
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.cli_aborts, 1);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.cli_aborts, 1);
 
 			rep->analysers &= AN_RES_FLT_END;
 			txn->status = 400;
@@ -1552,8 +1552,8 @@
 
 			HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 			if (objt_server(s->target)) {
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-				health_adjust(objt_server(s->target), HANA_STATUS_HTTP_BROKEN_PIPE);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+				health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_BROKEN_PIPE);
 			}
 
 			rep->analysers &= AN_RES_FLT_END;
@@ -1644,7 +1644,7 @@
 		stream_inc_http_err_ctr(s);
 
 	if (objt_server(s->target))
-		HA_ATOMIC_ADD(&objt_server(s->target)->counters.p.http.rsp[n], 1);
+		HA_ATOMIC_ADD(&__objt_server(s->target)->counters.p.http.rsp[n], 1);
 
 	/* Adjust server's health based on status code. Note: status codes 501
 	 * and 505 are triggered on demand by client request, so we must not
@@ -1652,9 +1652,9 @@
 	 */
 	if (objt_server(s->target)) {
 		if (txn->status >= 100 && (txn->status < 500 || txn->status == 501 || txn->status == 505))
-			health_adjust(objt_server(s->target), HANA_STATUS_HTTP_OK);
+			health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_OK);
 		else
-			health_adjust(objt_server(s->target), HANA_STATUS_HTTP_STS);
+			health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_STS);
 	}
 
 	/*
@@ -1764,8 +1764,8 @@
  return_bad_res:
 	HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 	if (objt_server(s->target)) {
-		HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-		health_adjust(objt_server(s->target), HANA_STATUS_HTTP_HDRRSP);
+		HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+		health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_HDRRSP);
 	}
 	txn->status = 502;
 	s->si[1].flags |= SI_FL_NOLINGER;
@@ -1885,7 +1885,7 @@
 		/* has the response been denied ? */
 		if (txn->flags & TX_SVDENY) {
 			if (objt_server(s->target))
-				HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_secu, 1);
+				HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_secu, 1);
 
 			HA_ATOMIC_ADD(&s->be->be_counters.denied_resp, 1);
 			HA_ATOMIC_ADD(&sess->fe->fe_counters.denied_resp, 1);
@@ -2072,8 +2072,8 @@
 
   return_bad_resp:
 	if (objt_server(s->target)) {
-		HA_ATOMIC_ADD(&objt_server(s->target)->counters.failed_resp, 1);
-		health_adjust(objt_server(s->target), HANA_STATUS_HTTP_RSP);
+		HA_ATOMIC_ADD(&__objt_server(s->target)->counters.failed_resp, 1);
+		health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_RSP);
 	}
 	HA_ATOMIC_ADD(&s->be->be_counters.failed_resp, 1);
 
@@ -2297,7 +2297,7 @@
 	res->analysers   &= AN_RES_FLT_END;
 	s->req.analysers &= AN_REQ_FLT_END; /* we're in data phase, we want to abort both directions */
 	if (objt_server(s->target))
-		health_adjust(objt_server(s->target), HANA_STATUS_HTTP_HDRRSP);
+		health_adjust(__objt_server(s->target), HANA_STATUS_HTTP_HDRRSP);
 
 	if (!(s->flags & SF_ERR_MASK))
 		s->flags |= SF_ERR_PRXCOND;
diff --git a/src/stream.c b/src/stream.c
index 5def7f1..ed913d1 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -352,7 +352,7 @@
 	if (objt_server(s->target)) { /* there may be requests left pending in queue */
 		if (s->flags & SF_CURR_SESS) {
 			s->flags &= ~SF_CURR_SESS;
-			HA_ATOMIC_SUB(&objt_server(s->target)->cur_sess, 1);
+			HA_ATOMIC_SUB(&__objt_server(s->target)->cur_sess, 1);
 		}
 		if (may_dequeue_tasks(objt_server(s->target), s->be))
 			process_srv_queue(objt_server(s->target));
@@ -713,7 +713,7 @@
 
 		if (s->flags & SF_CURR_SESS) {
 			s->flags &= ~SF_CURR_SESS;
-			HA_ATOMIC_SUB(&objt_server(s->target)->cur_sess, 1);
+			HA_ATOMIC_SUB(&__objt_server(s->target)->cur_sess, 1);
 		}
 
 		if ((si->flags & SI_FL_ERR) &&