egl/android: add a note about .swap_buffers_with_damage

egl/android: add a note about .swap_buffers_with_damage

Android implements the API and does the native damage handling itself.
At the same time it
 a) does call the vendor's eglSwapBuffersWithDamageKHR
 b) does not implement eglSetDamageRegionKHR

There's something strange happening here. For now simply note about the
'lack' of eglSwapBuffersWithDamageKHR support.

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