Platform GBM support eglGetDisplay
Created by: evelikov
The title says it all - the series addresses the missing support for GBM in GLVND.
Without it, older X (glamor in particular) and other applications that use eglGetDisplay() fail.
Furthermore due to a typo/thinko in the EGL_PLATFORM strings, one couldn't even force the correct platform. To top it up eglGetPlatformDisplay attrib_list was going to /dev/null.
FWIW the existing dladdr() trick is broken by design, since it will return false-positive even if one is using $plat_a while linking against correct $library_b. But that's topic for another day.