[lld] [lld][ELF][X86] Add missing X86_64_TPOFF64 case in switches (PR #77208)

[Nicholas Mosier via llvm-commits]

nmosier wrote:

> Drop `# 0x23 <_start+0x23>`
Done.

> You can add a comment that this additionally tests R_X86_86_TPOFF64
Done.

> Thanks. You can update the first comment,
Updated.

> It also helps to state which producer (GCC?) creates `R_X86_64_TPOFF64`. A psABI may define many not-so-useful relocation types and we may not support all of them.

Actually, it's LLVM/clang. I have submitted a concurrent patch for allowing LLVM to emit R_X86_64_TPOFF64 relocations, which a project I'm working on requires.

https://github.com/llvm/llvm-project/pull/77208