Extend conf-gnomecanvas support to MinGW and MSys2

[jmid]

Again, this is modeled after #26072

https://www.cygwin.com/packages/summary/mingw64-x86_64-libgnomecanvas2.html
https://www.cygwin.com/packages/summary/mingw64-i686-libgnomecanvas2.htm
and
https://packages.msys2.org/base/mingw-w64-libgnomecanvas

Note: the latter doesn't offer a i686 package.

[jmid]

I saw red lights and added

• OpenSuse support based on https://pkgs.org/search/?q=gnomecanvas - but found no "regular" Suse package there
• macPorts support based on https://ports.macports.org/port/libgnomecanvas/details/ - but found no homebrew package on https://formulae.brew.sh/

The CI will thus fail again on

• Suse and
• homebrew - I'm guessing the ["libgnomecanvas"] {os = "macos" & os-distribution = "homebrew"} line was OK at some point and then the package was removed from homebrew again...