mesa_glinterop: remove inclusion of GLX header

Since we only need partial information about the GLX symbols we can
forward declare them and drop the include. Obviously each user of the
said API will needs more than what's provides, so they'll include the
GLX header.

If they don't, the compiler will give us a nice warning ;-)

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Tested-by: Tom Stellard <thomas.stellard@amd.com>

include/GL/mesa_glinterop.h

@@ -51,13 +51,16 @@
 #define MESA_GLINTEROP_H
 
 #include <stddef.h>
-#include <GL/glx.h>
 #include <EGL/egl.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+/* Forward declarations to avoid inclusion of GL/glx.h */
+typedef struct _XDisplay Display;
+typedef struct __GLXcontextRec *GLXContext;
+
 /** Returned error codes. */
 enum {
    MESA_GLINTEROP_SUCCESS = 0,