cgi: add _GNU_SOURCE define to fix build error on musl

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/cgi.c b/cgi.c
index 62be0a3..a2a7e50 100644
--- a/cgi.c
+++ b/cgi.c
@@ -17,6 +17,7 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#define _GNU_SOURCE
 #include <libubox/blobmsg.h>
 #include "uhttpd.h"