[libcxx] [clang-tools-extra] [libcxxabi] [compiler-rt] [clang] [lldb] [lld] [flang] [llvm] [libc] [RISCV] Support Global Dynamic TLSDESC in the RISC-V backend (PR #66915)

[Fangrui Song via cfe-commits]

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

LGTM once the TLSDESC option is moved to use llvm/lib/CodeGen/CommandFlags.cpp

It's worth giving others some time to respond.

https://github.com/llvm/llvm-project/pull/66915