[lld] [LLD][MINGW] Add `--undefined-glob` flag support (PR #109866)

[Miguel A. Arroyo via llvm-commits]

mayanez wrote:

> It would be good to have a testcase on the COFF level, to validate this - I should have thought of this during the review of #109721, but I missed to request this.

Not a problem, I can open another PR to add this.

> This change looks fine, but I'd like to have the semantics of these options clarified (i.e. the questions above answered) before I merge this one.

These are the semantics I've observed:
* `--undefined-glob` (for LLD/ELF) does not necessitate a match. In other words, there is no error if there is no match. If a match is found, it treats it as if it was defined with `-u`. This makes sense since it isn't possible to define a strict requirement from the glob pattern.
  * This behavior corresponds to the following: 
    * https://github.com/llvm/llvm-project/blob/aeb18ebbe0a1a2fbce9b432eefed46c1d90968ea/lld/ELF/Driver.cpp#L2198-L2200
* `/includeglob:` similarly does not necessitate a match for the same reasons. I modeled the logic based on the logic for ELF. If a match is found, it treats it as if it was defined with `/include`.
  * https://github.com/llvm/llvm-project/blob/aeb18ebbe0a1a2fbce9b432eefed46c1d90968ea/lld/COFF/Driver.cpp#L716-L720 

I haven't taken a look yet to see if GNU ld is any different yet. However, let me know if the above makes sense.


https://github.com/llvm/llvm-project/pull/109866