win32: fix compilation again

While commit c02817e5 fixed compilation
without an installed libtool, moving the dependencies to rules.mak does
not work because the version-*-y variables are not defined yet.  Building
in a clean tree thus fails.

Revert the commit and remove the dummy /bin/false assignment to LIBTOOL.
This makes the build work, at the price of slightly worse errors when
there are Makefile bugs.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1367425815-15083-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>