* Skip building libcxx mt-only source files when single-threaded.
* This change is required for llvm18 libcxx.
* Add standalone test to link a trivial:
- mt-executable with libcxx
- st-executable with libcxx
2cd536d7e8Michael Dusan committed on 6/8/2024, 7:34:19 PM· committed by Andrew Kelleyparent6327a39