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 to automatically set
appropriate paths so 64-bit dmd compilation can be used outside of the
Visual Studio Command Prompt