The eglut_wayland event loop attempted to use frame events to drive the
redraw loop. However, the frame events were being requested after
eglSwapBuffers (i.e. wl_surface_commit()), which means they would not
actually activate until the next eglSwapBuffers.

This was being balanced out by 'redisplay' being set immediately by
es2gears, which would do an instant-return poll before calling
eglSwapBuffers, which would internally wait on its own frame event, and
as a side effect trigger the frame event that eglut_wayland had just
placed, causing redraw to be called again. The result would be a
stuttering 40fps.

Rewrite the event loop, so that:
  - frame events are placed before eglSwapBuffers is called
  - 'redisplay' no longer triggers an immediate return from poll
  - the frame event handler redraws if redisplay is requested, and
    exits if not
  - if redisplay is requested whilst we do not have a pending frame
    event, redraw instantly

Reported-by: Daniel van Vugt <daniel.van.vugt@canonical.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101814