Fixed SEH in fibers on Windows Server OSes.

[dnadlinger]

Windows Server 2008 and 2008 R2 validate the exception chain by default, so we need to install a Windows-internal default handler at the root of the chain. See in-code comment for details.

[dnadlinger]

@CyberShadow: Since I happen to know that you use a Windows Server box, could you please test the commit, if you have time?

[CyberShadow]

I can't seem to build this branch of druntime... the import target fails with:

dmd -c -d -o- -Isrc -Iimport -Hfimport\core\sys\posix\sys\un.di src\core\sys\posix\sys\un.d
src\core\sys\posix\sys\un.d(17): Error: import __anonymous sa_family_t not found
src\core\sys\posix\sys\un.d(17): Error: alias core.sys.posix.sys.un.sa_family_t recursive alias declaration

Edit: never mind, works after merging into master.

[CyberShadow]

Unittests pass for me.

[dnadlinger]

Okay, thanks (and rebased to latest master).

[braddr]

I know this is ancient code, but it's failing on windows server 2012 for 32 bit windows apps. See the thread I started on dmd-internal.

[dnadlinger]

Do the tests pass if you revert the change (and disable SEHOP)? Otherwise, broken EH in fibres is hardly related to this PR.

[braddr]

Daniel's investigations suggest while it looks similar, it might be a different cause for the same test to fail. He's digging into it, though more eyes couldn't hurt. I haven't tried reverting this change to see if it helps yet. I'm more focused on other things right now since disabling the tests isn't the end of the world.

[dnadlinger]

Okay, I see. Fibres being broken on Windows is sort of a big deal, given that vibe.d makes extensive use of them and there is std.concurrency.Scheduler now. However, I unfortunately have zero time to spend on this right now. The way I tracked the original issue down was spending a weekend with IDA and reverse-engineering the Windows SEH code. It's quite an interesting challenge because of all the userland-kernel gates (WoW64), but I still don't have a better suggestion on how to approach this.

[yebblies]

@klickverbot I tried disabling SEHOP and it didn't seem to make a difference.