fix winsound build with Visual Studio by only linking to libdl if not building with VS
fix winsound build with Visual Studio by only linking to libdl if not building with VS

nikhilsinghmus/csound,nikhilsinghmus/csound,nikhilsinghmus/csound,nikhilsinghmus/csound,nikhilsinghmus/csound,nikhilsinghmus/csound,nikhilsinghmus/csound,nikhilsinghmus/csound,nikhilsinghmus/csound,nikhilsinghmus/csound