resolv: try next server on SERVFAIL

Commit e1420eca7374cd8f583e9d774c890645a205aaee fixed a bug where a
response code should mean the next server is tried. However, it tries
only the next search domain, and never skips to the next server. This
fix makes sure we try the next server on SERVFAIL.

Signed-off-by: Michel Stam <michel@reverze.net>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

libc/inet/resolv.c

@@ -1471,9 +1471,11 @@ int __dns_lookup(const char *name,
 				}
 				/* no more search domains to try */
 			}
-			/* dont loop, this is "no such host" situation */
-			h_errno = HOST_NOT_FOUND;
-			goto fail1;
+			if (h.rcode != SERVFAIL) {
+				/* dont loop, this is "no such host" situation */
+				h_errno = HOST_NOT_FOUND;
+				goto fail1;
+			}
 		}
 		/* Insert other non-fatal errors here, which do not warrant
 		 * switching to next nameserver */