Changes

Do not statically link libgcc and libstdc++. (#1249)

* Do not statically link libgcc and libstdc++.

  - This is not recommend in general but it is also not good for us
    specifically. To begin with, it just assumes the compiler is always
    `gcc`. Compiling OMSimulator with, for example, MinGW64 clang and then linking
    to libstdc++ instead of libc++ will, in the least, give you those warnings
    about duplicate sections having different sizes. For other
    compilers/runtimes it can have a more serious effect. I think it segfaults
    for clang on MinGW-64's UCRT system.

  - There is no need for this. The only benefit of it was probably not having
    to ship libgcc and libstdc++ with the OMSimulator binaries when making
    a package from the MinGW build. However, there is an MSVC build for
    Windows and that should be the one used for creating real Windows packages.
    The MinGW packages should be used for MSYS/MinGW systems only.

* Remove CI job for checking Windows executables on Linux+Wine

  - This is not needed anymore. One can always build the native binary
    on Linux.