Tests: Allow tests to function without VVLs. This is necessary to run angle_end2end_tests with sanitizers. We don't currently support building the VVL in sanitized configs. Bug: b/168744561 Change-Id: If16a25ac5786f5f5aeb8ae50d9f7fa22c6c87995 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2415513 Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com> Reviewed-by: Tim Van Patten <timvp@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>