config: disable thread safety analysis on COFF

clang cannot properly handle __declspec and __attribute__ on classes
right now.  This prevents the shared_mutex tests from working.  Disable
the use of the annotation on COFF targets.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@294958 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed