New sc.ini with expanded 64-bit support

Note: Requires phobos64.lib to be in lib64 rather than lib (see [phobos pull 1652](https://github.com/D-Programming-Language/phobos/pull/1652))

Fixes issue #11266

Should work for all versions of Visual Studio 2008+ when dmd is used within the Visual Studio Command Prompt.

Works in conjunction with the Windows dmd installer (see [installer pull 22](https://github.com/D-Programming-Language/installer/pull/22)) to automatically set appropriate paths so 64-bit dmd compilation can be used outside of the Visual Studio Command Prompt