[libcxxabi] __cxa_guard_require: test guard byte with != 0 instead of == 1 am: 6f1796448f am: bda6af8573

Original change: https://android-review.googlesource.com/c/platform/external/libcxxabi/+/1727437

Change-Id: I545308a3eed105c4e198d5b522c31603589f1355