GLES1: Correct 'active' attributes mask. The active attributes are those consumed by the Program. Previously we were returning those enabled as client arrays. But this excluded default attributes. Uncovered when changing how resource usage was tracked for Vulkan multithreading. Bug: angleproject:2464 Change-Id: I48996be9e4470bb1432e042f98046c95ea8adbfe Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1808718 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Geoff Lang <geofflang@chromium.org>