gl-renderer: move all EGL_PLATFORM_* defines here

Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/gl-renderer.h b/src/gl-renderer.h
index 9e4b220..2434fdd 100644
--- a/src/gl-renderer.h
+++ b/src/gl-renderer.h
@@ -39,6 +39,18 @@
 typedef intptr_t EGLNativeWindowType;
 #define EGL_DEFAULT_DISPLAY ((EGLNativeDisplayType)0)
 
+#endif /* ENABLE_EGL */
+
+#ifndef EGL_PLATFORM_GBM_KHR
+#define EGL_PLATFORM_GBM_KHR 0x31D7
+#endif
+
+#ifndef EGL_PLATFORM_WAYLAND_KHR
+#define EGL_PLATFORM_WAYLAND_KHR 0x31D8
+#endif
+
+#ifndef EGL_PLATFORM_X11_KHR
+#define EGL_PLATFORM_X11_KHR 0x31D5
 #endif
 
 enum gl_renderer_border_side {