Hans de Goede authored Dec 20, 2016 and Adam Jackson committed Jan 02, 2017

If the libEGL we are using has eglGetPlatformDisplayEXT, yet it still
returns NULL, then this very likely means that it does not support the
type (e.g. EGL_PLATFORM_GBM_MESA) passed in, and then returning NULL is
the right thing to do.

This avoids falling back to an eglGetDisplay() implementation which does
not understands the passed in gbm handle, treats it as a pointer to
something else completely, followed by a crash sooner or later.

Specifically this fixes using the nvidia binary driver, with nvidia's
libEGL + the modesetting driver on a secondary GPU crashing inside
glamor_egl_init() sometimes.

Cc: Eric Anholt <eric@anholt.net>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>