Add -Zindirect-branch-cs-prefix

[Darksonn]

cc @ojeda

[bjorn3]

What exactly does Linux need this for?

[Darksonn]

I will add more info to the PR description before removing the draft marker, but for now please see #116852 (comment) and the original clang change.

[ojeda]

I was looking into this last week and I think this needs a few more things, and should probably go into (or on top of) @azhogin's #135927, since that allows us to test it properly (and I think it does not make much sense without it?).

I sent a draft PR at #140740 -- please feel free to take the commit into your PR @azhogin. (I rebased @azhogin's there, and I added a Co-developed-by because I wasn't sure how to split it).

It additionally contains the assembly test for call and jmp, the docs and the invalid flag test.

[ojeda]

I have kept the commit from here just in case and to show the difference/additions.

[ojeda]

@rustbot label F-target_modifiers A-rust-for-linux

[Darksonn]

Closing in favor of #140740.