When to drop src/tools/msvc support

Hi,

I'd planned to write this soon anyway, but it was just brought up in [1].

Originally we had planned to drop src/tools/msvc support shortly after meson
went in. Unfortunately, it took a bit longer than originally hoped for to
merge meson support and then longer than hoped to add buildfarm support. I
don't think there's been any buildfarm client release with meson support yet -
but we do have windows buildfarm animals using it.

Do we want to drop src/tools/msvc support in 16 (i.e. now), or do it early in
17?

I do have a set of patches removing src/tools/msvc. There are a few loose ends
that I know of (my eyes glaze over every time I try to reconcile the
src/tools/perl.m4 comments with the referenced comments in Mkvcbuild.pm), and
probably more small references that grep terms didn't find.

Greetings,

Andres Freund

[1] https://postgr.es/m/3598664.1680976414%40sss.pgh.pa.us