dev-util/w32api, dev-util/mingw-runtime: drop packages

dev-util/w32api, dev-util/mingw-runtime: drop packages

Drop mingw-runtime-based packages. Use mingw64-runtime-based ones instead.

Here are example mingw64-based tuples to use:
- i686-w64-mingw32 (equivalent of mingw32)
- x86_64-w64-mingw32 (equivalent on migw64?)

crossdev can be used to recreate new cross-environment.

Closes: https://bugs.gentoo.org/584858
Closes: https://bugs.gentoo.org/511492
Closes: https://bugs.gentoo.org/568500
Closes: https://bugs.gentoo.org/574556
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>