[lld] [lld][ELF] Implement merged .debug_names section. (PR #86508)

[via llvm-commits]

cmtice wrote:

> > > `driver.test` has `error: -r and --gdb-index may not be used together`. Add --debug-names test there.
> > 
> > 
> > Done (see 'debug-names-invalid-flags.s).
> 
> When I suggested add the test there, I am very clear that we should reuse an existing test, instead of disobeying the convention and adding a new file. There are values in reusing a small set of files instead of spreading tests everywhere.
> 
> I can take a stab at providing an update on top of this branch so that we don't need to spend too much time debating detailed changes, and you can then consider cherry picking my commits. I believe my providing commits directly might expedite this patch.

I apologize! I mis-read your original request.  I have fixed it now (added the test to driver.test and removed debug-names-invalid-flags.s).

https://github.com/llvm/llvm-project/pull/86508