Bugfix from Atsushi Nemoto: return nonzero error code on failure

(without which busybox ping segfaults on error).  Broken during locking
changes in in svn 16801.

libc/inet/getproto.c

@@ -195,7 +195,7 @@ again:
     rv = 0;
 DONE:
     __UCLIBC_MUTEX_UNLOCK(mylock);
-    return 0;
+    return rv;
 }
 libc_hidden_def(getprotoent_r)