[llvm] [llvm-objcopy] Add SystemZ support (PR #81841)

[Ulrich Weigand via llvm-commits]

uweigand wrote:

> Looks good, except it looks like we document the supported formats in the CommandGuide (see https://llvm.org/docs/CommandGuide/llvm-objcopy.html#supported-formats). Unfortunately, it looks like some of the newer ones are missing from that. If you're okay with doing so, it would be great if you could provide another PR that adds the remaining missing ones (I think it's just hexagon and loongarch, but could be wrong).

Submitted as https://github.com/llvm/llvm-project/pull/81981, thanks!

https://github.com/llvm/llvm-project/pull/81841