dri_interface.h: add missing stdint.h include

Required for uint32_t and friends.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

include/GL/internal/dri_interface.h

@@ -48,6 +48,8 @@ typedef unsigned int drm_drawable_t;
 typedef struct drm_clip_rect drm_clip_rect_t;
 #endif
 
+#include <stdint.h>
+
 /**
  * \name DRI interface structures
  *