Add a basic GLX EGL implementation BUG=angleproject:892 Change-Id: Ife9955a457d4a6fb3adce17757ccb0de7d0dd274 Reviewed-on: https://chromium-review.googlesource.com/269413 Reviewed-by: Geoff Lang <geofflang@chromium.org> Tested-by: Corentin Wallez <cwallez@chromium.org>