include cleanups: remove unused headers and add feature test macros

[musl] / src / process / vfork.c

diff --git a/src/process/vfork.c b/src/process/vfork.c
index 16d07ea..fc4adb4 100644 (file)
--- a/src/process/vfork.c
+++ b/src/process/vfork.c
@@ -1,3 +1,4 @@
+#define _GNU_SOURCE
 #include <unistd.h>
 #include "syscall.h"
 #include "libc.h"