CalculiX i8 and mingw

[rafal.brzegowy]

Finally arpack i8 is available in msys2/mingw64 repo:

continuation arpack: switch to cmake (ninja) and create split package with 32-bit and 64-bit indexing

https://packages.msys2.org/package/mingw-w64-x86_64-arpack64?repo=mingw64

Makefile: -larpack_64