It appears that the C++ standard allows overriding destructors to be marked
"override," but at least some MSVC versions complain about it, so at least make
sure such destructors are explicitly marked "virtual."
Change-Id: I0e1cafa7584fd16ebdce61f569eae2373a71b0a1
...mostly done with a rewriting Clang plugin, with just some manual tweaking
necessary to fix poor macro usage.
Change-Id: Ie656f9d653fc716f72ac175925272696d509038f
