[lld] [PAC][ELF] Remove NEEDS_{GOT,TLSDESC}_NONAUTH (PR #213452)

[Jessica Clarke via llvm-commits]

jrtc27 wrote:

The context of this is that we are currently using 4 additional flags bits downstream[^1], and as of https://github.com/llvm/llvm-project/commit/6a874161621ec52b8efa125790e3e8e72bb9167a there are only 3 left. This is an easy way to reclaim 2, so the PAC implementation goes from consuming 4 extra bits, i.e. 25%, to "just" 2. Things are still very tight, but we can probably scrape by for now.

[^1]: Due to having a separate TLS ABI that has its own bits. Upstream we could just repurpose the existing TLS ones (and add the single extra one that doesn't map to any of the existing ones), but for Morello we have a rather cursed "transitional"/"compat" ABI that supports both simultaneously within the same object and so does need them to be orthogonal. This will never be upstreamed, though, and we can probably drop it downstream eventually, even.

https://github.com/llvm/llvm-project/pull/213452