Be sure to clear all program state at unlink At Program::unlink we clear out the program's state but forgot mBufferVariables. That was causing us to hit an assert when trying to load a shader from cache. Only see the issue on Android as that's the only platform where shader caching is supported. Test: KHR-GLES31.core.explicit_uniform_location.uniform-loc Bug: angleproject:4132 Change-Id: Iae9c26a3e3b2d11983cc7d90bcd54a10c0fa9934 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2107235 Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>