GL: Temporarily disable MSRTT on Android. This extension is causing validation errors and graphics corruption in Chrome. Disable it until the bugs are resolved. Bug: chromium:1238327 Change-Id: I823303f2d75f2d6422cf5680a8751b9b79c8580b Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3149573 Reviewed-by: Peng Huang <penghuang@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>