A large part of the packaging is shared in package.sh, this approach should
work on windows with another dll list in package-waves.sh and redefined
copydll function(which I've added untested as copydll-waves.sh)
Also add support for 64bit mingw builds via ARCH env variable. If unset
defaults to 32bit build
These scripts are too specific to my virtual machine setup, a more generic
method can now be used by setting ARDOUR_VM_SHARE_DIR and using the
cptovmshare.sh script.
