Don't include x11-specific code in test_renderer_generic when
use_x11 is set to false.
Bug: webrtc:8500
Change-Id: If64305e63484b985d90a9c9381bd391e34db3e26
Reviewed-on: https://webrtc-review.googlesource.com/21000
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Edward Lemur <ehmaldonado@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20602}