Fixes android-custom-car toolchain builds failing because v8_context_snapshot_generator couldn't load libx11.so.6 at runtime. The generator is a host x64 binary that runs during the Android cross-compile. The linux64 docker image already had a full set of x11 runtime libs; the android one didn't. Rather than add just the one missing lib, this patch brings the android image up to the same set as linux64. Differential Revision: https://phabricator.services.mozilla.com/D308259