BUG/MINOR: resolvers: Add missing case-insensitive comparisons of DNS hostnames

DNS hostname comparisons were fixed to be case-insensitive (see b17b88487
"BUG/MEDIUM: dns: Consider the fact that dns answers are
case-insensitive"). However 2 comparisons are still case-sensitive.

This patch must be backported as far as 1.8.
diff --git a/src/server.c b/src/server.c
index ee5bbac..8935a6a 100644
--- a/src/server.c
+++ b/src/server.c
@@ -3364,7 +3364,7 @@
 		HA_SPIN_LOCK(SERVER_LOCK, &tmpsrv->lock);
 		if ((tmpsrv->hostname_dn == NULL) ||
 		    (srv->hostname_dn_len != tmpsrv->hostname_dn_len) ||
-		    (strcmp(srv->hostname_dn, tmpsrv->hostname_dn) != 0) ||
+		    (strcasecmp(srv->hostname_dn, tmpsrv->hostname_dn) != 0) ||
 		    (srv->puid == tmpsrv->puid)) {
 			HA_SPIN_UNLOCK(SERVER_LOCK, &tmpsrv->lock);
 			continue;
@@ -3443,7 +3443,8 @@
 	resolution = (srv->resolv_requester ? srv->resolv_requester->resolution : NULL);
 	if (resolution &&
 	    resolution->hostname_dn &&
-	    strcmp(resolution->hostname_dn, hostname_dn) == 0)
+	    resolution->hostname_dn_len == hostname_dn_len &&
+	    strcasecmp(resolution->hostname_dn, hostname_dn) == 0)
 		goto end;
 
 	resolv_unlink_resolution(srv->resolv_requester, 0);