Fix LLD_LINK descriptions

[dim]

Summary

Currently, the LLD_LINK option is described as "Link ld.lld as ld to
clang uses it". I'm not a native English speaker, but this seems like a
typo. Probably "so" instead of "to" was meant? I also propose to add a
comma, to make it a little clearer.

That said, for e.g. llvm11 and 12, I don't really see how the option is
actually implemented, so maybe it can be ditched anyway? For llvm90,
there is a fragment in the Makefile that has:

post-install-LLD_LINK-on:
	${LN} -s ld.lld ${STAGEDIR}${LLVM_PREFIX}/bin/ld

but I see no such thing for the later llvm ports.

[brooks]

Thanks for the better wording. As you noticed, LLD_LINK doesn't do anything in llvm10 and later (the link is made unconditionally). I think I'd like to go ahead and commit the change to llvm90 immediately because I don't think it will trigger rebuilds, but check that there aren't other changes I should be making to 11-12 before deleting the options since that definitely triggers a rebuild in poudriere.

[brooks]

Sigh, I committed the changes and had pasted in the wrong review url. Accepting so I can close...