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

[Min-Yih Hsu via llvm-commits]

mshockwave wrote:

> Isn't the too large offset what the linker in the above `rustc` build is complaining about?

Correct.
`_GLOBAL_OFFSET_TABLE_` pointed to the _beginning_ of the GOT, even if we're able to materialize it when it's over 16 bits, -- which I believe is what this patch does -- that still doesn't solve the problem as the _offset_ to, for example the 9000-th GOT entry, still cannot fit into 16 bits. 

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