sdk: Common: Add stdint.h include to platform_utils.hpp for GCC 13+

GCC 13 seems to have changed some implicit includes in standard headers, and
now `stdint.h` needs to be included explicitly to use `uint16_t` in this file.

Author: akien-mga

changes/sdk/pr.406.gh.OpenXR-SDK-Source.md

@@ -0,0 +1 @@
+Common: Add `stdint.h` include to `platform_utils.hpp` for GCC 13+

src/common/platform_utils.hpp

@@ -11,6 +11,7 @@
 
 #include "xr_dependencies.h"
 #include <string>
+#include <stdint.h>
 #include <stdlib.h>
 
 // OpenXR paths and registry key locations