[Driver] Don't pass -Z to ld for ELF platforms (#69120)

-Z is an Apple ld64 option. ELF linkers don't recognize -Z, except
OpenBSD which patched GNU ld to add -Z for zmagic (seems unused)

> -Z Produce 'Standard' executables, disables Writable XOR Executable
features in resulting binaries.

Some `ToolChain`s have -Z due to copy-and-paste mistakes.