From c90640fae5aeb54c9569558447d7f51355d0368a Mon Sep 17 00:00:00 2001
From: Pedro Gonnet <gonnet@google.com>
Date: Thu, 9 Jan 2025 13:31:02 -0800
Subject: [PATCH] Wrap `#define _GNU_SOURCE` in an `#ifndef` in case it has
 already been defined.

PiperOrigin-RevId: 713777960

diff --git a/src/pthreads.c b/src/pthreads.c
index 6f7829f..237edd2 100644
--- a/src/pthreads.c
+++ b/src/pthreads.c
@@ -8,7 +8,9 @@
 // LICENSE file in the root directory of this source tree.
 
 // Needed for syscall.
-#define _GNU_SOURCE
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#endif  // _GNU_SOURCE
 
 /* Standard C headers */
 #include <assert.h>