egl/wayland: Add invalidate back in eglSwapBuffers()

egl/wayland: Add invalidate back in eglSwapBuffers()

Commit ca3ed3e024864e91ca3cccc59fb96950e1d079b5 fixed the problem where
eglMakeCurrent would trigger a getbuffer callback that then breaks the
following wl_egl_window_resize() call.  However, we still need to
invalidate buffers in eglSwapBuffers, since in wayland we always swap
buffers, so the dri driver needs to come out and ask us for the next buffer
after each swapbuffer.

Note: this is a candidate for stable branches.

Signed-off-by: Kristian Høgsberg <krh@bitplanet.net>