Fix compilation with clang

From https://github.com/msys2/MINGW-packages/pull/9509

diff --git a/gtk/gtklabel.c b/gtk/gtklabel.c
index e0f5565b840ca977f9de8c6008f9c523077842c7..c2a108aab3c1f342f59ab2f882db6c90ea099066 100644 (file)
--- a/gtk/gtklabel.c
+++ b/gtk/gtklabel.c
@@ -55,6 +55,7 @@
 #include "gtkjoinedmenuprivate.h"
 
 #include <math.h>
+#include <stdlib.h>
 #include <string.h>
 
 /**