add msys2/ucrt64 and msys2/clang64 repositories

[ognevny]

Title

MSYS2/UCRT and MSYS2/CLANG

Repository data location(s)

• http://repo.msys2.org/{ucrt64,clang64}/{ucrt64,clang64}.db.tar.zst

Package links

• Recipe: https://github.com/msys2/MINGW-packages/blob/master/mingw-w64-{pkgname}/PKGBUILD
• Package page: https://packages.msys2.org/package/mingw-w64-ucrt-x86_64-{pkgname}?repo=ucrt64 (ucrt64)
  https://packages.msys2.org/package/mingw-w64-clang-x86_64-{pkgname}?repo=clang64 (clang64)
• Package sources: https://github.com/msys2/MINGW-packages/blob/master/mingw-w64-{pkgname}/
• Issues: https://github.com/msys2/MINGW-packages/issues
• Build status: https://packages.msys2.org/queue
• Build log: https://github.com/msys2/msys2-autobuild/actions/workflows/build.yml

Additional details

note: there are mingw32 and mingw64 repos presented. currently more than half packages are not supported for i686 (removed from repo), some new packages also don't have a mingw64 version