More CI tragets: Linux 32bit, LTO, Windows and Cosmopolitan

More CI tragets: Linux 32bit, LTO, Windows and Cosmopolitan

Atomics support in Windows requires libwinpthread*.dll at runtime. One
way to get it is to install it with MinGW package, and copy alongside
the executable.

Update test Makefile targets for windows executables.

Allow running tests with Wine: `make WINE=wine CONFIG_WIN3=y
...`. That's useful when Wine binfmt support cannot be installed such
as on the CI hosts.

Add PPC64LE architecture and try to fix flaky multi-arch CI in gcc:
https://github.com/tonistiigi/binfmt/issues/215