gnu: itstool: Add propagated inputs python-2 and libxml2.

* gnu/packages/glib.scm (itstool): Add propagated input python-2; it is needed
    to rewrite the shebang in the output python script and must be propagated
    so that PYTHONPATH gets set when using itstool; and libxml2, imported as a
    module by the script.

gnu/packages/glib.scm

@@ -264,6 +264,8 @@ (define itstool
               (base32
                "1akq75aflihm3y7js8biy7b5mw2g11vl8yq90gydnwlwp0zxdzj6"))))
     (build-system gnu-build-system)
+    (inputs
+     `(("python-wrapper" ,python-wrapper)))
     (home-page "http://www.itstool.org")
     (synopsis "Tool to translate XML documents with PO files")
     (description