[clang] [llvm] [RISCV] Enable TLSDESC by default (PR #166540)

[Palmer Dabbelt via llvm-commits]

palmer-dabbelt wrote:

just FYI: @thesamesam brought this up over in GCC land https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122565#c5

https://github.com/llvm/llvm-project/pull/166540