[llvm] [M68k] implement -mxgot (PR #119803)

[Min-Yih Hsu via llvm-commits]

mshockwave wrote:

> @mshockwave Anything you could do to help with this?
> 
> FWIW, we have the full M68000 SysV ELF ABI available now, see: https://people.debian.org/~glaubitz/m68k-sysv-abi.pdf

Oh I thought this is still a draft PR and that's why it didn't pop up in my radar. @knickish is this ready for review?

https://github.com/llvm/llvm-project/pull/119803