Suppress warning "_GNU_SOURCE" redefined

libc/sysdeps/linux/common/euidaccess.c:1:1: warning: "_GNU_SOURCE" redefined
In file included from <command-line>:0:
./include/libc-symbols.h:52:1: warning: this is the location of the previous definition

Signed-Off-By: Leonid Lisovskiy <lly.dev@gmail.com>

libc/sysdeps/linux/common/euidaccess.c

@@ -1,4 +1,3 @@
-#define _GNU_SOURCE
 #include <unistd.h>
 #include <fcntl.h>