include stdint.h for int32_t/uint32_t

Signed-off-by: Jussi Kukkonen <jussi.kukkonen@intel.com>
Reviewed-by: Yong Bakos <ybakos@humanoriented.com>
diff --git a/clients/window.h b/clients/window.h
index 97719a7..1ad3b4f 100644
--- a/clients/window.h
+++ b/clients/window.h
@@ -26,6 +26,7 @@
 
 #include "config.h"
 
+#include <stdint.h>
 #include <xkbcommon/xkbcommon.h>
 #include <wayland-client.h>
 #include <cairo.h>