[lld][MachO] Implement support for `-allowable_client`

[carlocab]

This is a follow-up to #114638 and #114146.

In #114638, we implemented support for respecting the allowable-client fields in libraries that were linked with -allowable_client. It is currently only possible to produce these libraries using Apple ld64.

We should teach ld64.lld to do the same. This will allow us to get rid of the liballowable_client.dylib binary test fixture (used in allowable-client.s).

It suffices to populate the LC_SUB_CLIENT field(s) in the MachO header with the name(s) passed to -allowable_client.

I plan to work on this myself, but I've opened this to make sure this is being tracked somewhere (in case I don't get to it).

[llvmbot]

@llvm/issue-subscribers-lld-macho

Author: Carlo Cabrera (carlocab)

This is a follow-up to #114638 and #114146.

In #114638, we implemented support for respecting the allowable-client fields in libraries that were linked with -allowable_client. It is currently only possible to produce these libraries using Apple ld64.

We should teach ld64.lld to do the same. This will allow us to get rid of the liballowable_client.dylib binary test fixture (used in allowable-client.s).

It suffices to populate the LC_SUB_CLIENT field(s) in the MachO header with the name(s) passed to -allowable_client.

I plan to work on this myself, but I've opened this to make sure this is being tracked somewhere (in case I don't get to it).