Fix PR#41323 'Race condition in steady_clock::now for _LIBCPP_WIN32API'. thanks to Ivan Afanasyev for the report.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@357413 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed