simple-egl: remove incomplete EGL_EXT_buffer_age definition

A more complete alternative is already provided by the weston-egl-ext.h
header. The latter of which we already include.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>

clients/simple-egl.c

@@ -50,11 +50,6 @@
 #include "shared/platform.h"
 #include "weston-egl-ext.h"
 
-#ifndef EGL_EXT_buffer_age
-#define EGL_EXT_buffer_age 1
-#define EGL_BUFFER_AGE_EXT			0x313D
-#endif
-
 struct window;
 struct seat;