Support standalone Android builds in ANGLE. By disabling apk generation, we can build all of our targets in a standalone ANGLE checkout on Linux. This allows tools like gn desc to give us useful information about Android builds. BUG=angleproject:4026,angleproject:2344 Change-Id: Ic46348fd06c5174ce5e5a4d89ceb391246c6ac6b Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1866080 Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com> Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>