linux: enable angle gl for wayland only builds. Chromium is unable to use angle gl implementation if it's a wayland only build as angle_use_x11 is false then. This CL fixes that and allows Chromium Wayland only build use angle GL. Bug: chromium:1231934 Change-Id: Ic4363b986abd6453865f63111032ac810fafc8de Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3295616 Commit-Queue: Yuly Novikov <ynovikov@chromium.org> Reviewed-by: Yuly Novikov <ynovikov@chromium.org>