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

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@369109 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit ab4302de162a1de64cdd8d51351858834cc926be)

Bug: http://b/189279320
Test: treehugger
Change-Id: Ia47ad2f2f95d343adb30eb46c0043c76f5885195
1 file changed