[compiler-rt] [libcxxabi] [lld] [lldb] [clang] [llvm] [libc] [libclc] [libunwind] [libcxx] [clang-tools-extra] [flang] [builtins] Generate __multc3 for z/OS (PR #77554)

[Alexander Richardson via cfe-commits]

https://github.com/arichardson approved this pull request.

Thanks this looks good to me now and should not change anything for other targets.

https://github.com/llvm/llvm-project/pull/77554