eglGetProcAddress() returns non-null function pointers
whether or not they're actually supported by the driver,
since it can be used before any driver gets loaded. So
we have to check if the extensions are advertised first,
which requires having an initialized display, so we split
the display creation code into its own function.
The exception to extension-checking is EGL_MESA_drm_display,
since by definition it's needed before any display is even
created.
Adapt to changes from this Wayland commit:
"Update surface.attach and change surface.map to surface.map_toplevel"
(82da52b15b49da3f3c7b4bd85d334ddfaa375ebc)
Adapt to changes from these wayland commits:
35fd2a8cc68c42d90756330535de04cbbb4d2613
2bb3ebe1e437acf836449f0a63f3264ad29566f2
f8fc08f77187f6a5723281dab66841e5f3c24320
http://bugzilla.clutter-project.org/show_bug.cgi?id=2474
Always use pageflipping, but avoid full repaint by copying back dirty
regions from front to back. Additionally, we dealy copying back until
we're ready to paint the new frame, so we can avoid copying areas that
will be repainted anyway.
This is the least amount of copying per frame we can get away with at all
and at the same time we don't have to worry about stalling the GPU on
synchronized blits since we always pageflip.
