remote: use xstrdup() instead of strdup()

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

remote.c

@@ -815,7 +815,7 @@ char *apply_refspecs(struct refspec *refspecs, int nr_refspec,
 						    refspec->dst, &ret))
 				return ret;
 		} else if (!strcmp(refspec->src, name))
-			return strdup(refspec->dst);
+			return xstrdup(refspec->dst);
 	}
 	return NULL;
 }