Implement fuzzy EGLConfig pixel format matching, where we ensure that R, G, B
and A channels have the expected number of bits exactly. This is used on EGL
platforms where the EGLConfig native visual ID is not a DRM format code. On EGL
GBM platform, the old exact matching of native visual ID is kept.
As only the DRM backend uses a DRM format list for picking a config, this patch
should not change any behaviour.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>