glamor: Assume EGL in glamor_context

Reviewed-by: Emma Anholt <emma@anholt.net>
5 jobs for xephyr-glamor-egl in 6 minutes and 33 seconds (queued for 1 second)
Status Name Job ID Coverage
  Docker Image
passed debian-buster #13702552

00:00:20

 
  Build And Test
passed autotools #13702553

00:06:13

passed meson #13702554

00:02:39

passed meson-noglamor #13702555

00:02:27

passed mingw-cross-build #13702556

00:00:47