Add thread cleanup test

This adds a test that creates an EGL context and surface, destroys
them while they're still current, and then exits the current thread.
If our EGL implementation isn't cleaning up on thread exit, we run
out of resources quickly and crash or are killed.

Bug 9209776

Change-Id: I46a6f21e8d0bfef58c9d22c90201d74c895487ae