Continue loop if space for hostname not large enough

When attempting to build a search domain from the local hostname
(used as a fallback when no other methods have given a search
domain), the code doubles the buffer size on each loop iteration.

However, the loop previously had a WHILE_FALSE terminator so the continue
statement exited the loop rather than going round again.

ares_init.c

@@ -1409,7 +1409,7 @@ static int init_by_defaults(ares_channel channel)
         goto error;
       }
 
-    } WHILE_FALSE;
+    } while (res != 0);
 
     dot = strchr(hostname, '.');
     if (dot) {