llvm

d15fad26 - [libc++][libc++abi] Fix or suppress failing tests in single-threaded

[libc++][libc++abi] Fix or suppress failing tests in single-threaded builds. Fix a libc++abi test that was incorrectly checking for threading primitives even when threading was disabled. Additionally, temporarily XFAIL some module tests that fail because the <atomic> header is unsupported but still built as a part of the std module. To properly address this libc++ would either need to produce a different module.modulemap for single-threaded configurations, or it would need to make the <atomic> header not hard-error and instead be empty for single-threaded configurations