weston-egl-ext.h: add EGL_EXT_swap_buffers_with_damage definitions

... and use it from simple-egl and gl-renderer.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
diff --git a/clients/simple-egl.c b/clients/simple-egl.c
index d8233c1..6b4f1a1 100644
--- a/clients/simple-egl.c
+++ b/clients/simple-egl.c
@@ -48,11 +48,7 @@
 #define IVI_SURFACE_ID 9000
 
 #include "shared/platform.h"
-
-#ifndef EGL_EXT_swap_buffers_with_damage
-#define EGL_EXT_swap_buffers_with_damage 1
-typedef EGLBoolean (EGLAPIENTRYP PFNEGLSWAPBUFFERSWITHDAMAGEEXTPROC)(EGLDisplay dpy, EGLSurface surface, EGLint *rects, EGLint n_rects);
-#endif
+#include "weston-egl-ext.h"
 
 #ifndef EGL_EXT_buffer_age
 #define EGL_EXT_buffer_age 1