Distribute virtualenv_mod in the windows packages

Due to an oversight the virtualenv_mod module was not distributes with
the Windows package anymore.

Author: Lesvek

pkg/windows/msi/build_pkg.ps1

@@ -359,7 +359,7 @@ $modules = "acme",
            "uswgi",
            "varnish",
            "vbox",
-           "virt",
+           "virt.py",  # We don't want to remove virtualenv_mod.py
            "xapi",
            "xbpspkg",
            "xfs",

pkg/windows/nsis/build_pkg.ps1

@@ -261,7 +261,7 @@ $modules = "acme",
            "uswgi",
            "varnish",
            "vbox",
-           "virt",
+           "virt.py",  # We don't want to remove virtualenv_mod.py
            "xapi",
            "xbpspkg",
            "xfs",