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

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

Change-Id: I3fb89a60b183c94b1831962041f62d9ef66a4e62