[llvm] [CodeGen][X86] Fix lowering of tailcalls when `-ms-hotpatch` is used (PR #77245)

[Shengchen Kan via llvm-commits]

KanRobert wrote:

@sylvain-audi
For 1, I think we can avoid introducing the wrapper `PATCHABLE_OP` and instead add `MIFlag` (/llvm/include/llvm/CodeGen/MachineInstr.h) for your purpose.

For 2, instruction length is only determined before emitting. I think it's impossible to know that in `PatchableFunction`. if the size is always 2, we should not overdesign.

https://github.com/llvm/llvm-project/pull/77245