Add support for Dwarf5 as emitted by gcc-11.2

[neerajsi-msft]

This PR implements enough dwarf5 support to produce PDBs for git-for-windows.

Please see the individual commits for layered changes. I'd be happy to take another stab at re-layering if that would help drive this change to acceptance.

[neerajsi-msft]

@dscho : This is the full dwarf5 PR.

[rainers]

Thanks for your contribution. Now that the D compiler in the gcc suite will be uptodate with current D versions, this might also become interesting for the D community, again.

I only had a cursory look so far, looks good. I'll have a closer look in the next couple of days.

[dscho]

Now that there are github actions available, is there a way to add tests?

Yes!

Something like this should work: https://github.com/dscho/cv2pdb/commit/13a21e913a1bdeaba5eeba4c66f7ae08e0596a1a (it passed the build here)

The CI still uses VS2017, I'm not sure how well this works with constexpr.

Maybe we need to extend the GitHub workflow to also build with VS2017? The big problem here is that the VS2017 build agents will be removed in less than half a year: https://github.com/actions/virtual-environments/issues/4312.

[rainers]

Maybe we need to extend the GitHub workflow to also build with VS2017?

I don' t think that's necessary. I'd rather update the appveyor build at some time or move the CI for Visual D to github, too.

[dscho]

Something like this should work: dscho@13a21e9

@neerajsi-msft how about fast-forwarding your branch to that commit?

[neerajsi-msft]

@dscho: Done. Thanks!

[rainers]

Thanks!

[dscho]

@rainers could I ask for a new tagged version with this?

[rainers]

Available now: https://github.com/rainers/cv2pdb/releases/tag/v0.50

[dscho]

Available now: https://github.com/rainers/cv2pdb/releases/tag/v0.50

Thank you!