X11 and Ozone: fallback to X11 backend for tests.
X11 and Ozone: fallback to X11 backend for tests.

USE_X11 && USE_OZONE build is a new config for
Chromium/Linux that is going to be enabled soon.
However, it breaks angle tests for Linux bots that
run these tests. Atm, we don't support Wayland
in angle anyway, and always falling back to X11
is the right thing to do.

However, it's a bit strange to return false in
IsOzone for USE_X11 && USE_OZONE case, but it's
something we can do now to unblock switching
Chromium to use_x11 && use_ozone config for
Linux and resolve the problem later.

Bug: angleproject:4977
Bug: chromium:1085700
Change-Id: Id223110cc504d8a4faa38608a96338a297a8cfc3
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2367856
Reviewed-by: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>
Commit-Queue: Shahbaz Youssefi <582eeec4f08a2ccd61e3ef52115e6e7c571582de@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle