po: add its rules for translating polkit file strings

xgettext / msgfmt have generic support for extracting / merging strings
in XML files, however, they need to be told something about the schema
to know which fields are translatable. This is done by providing 'its'
rules. Usually the 'its' rules would be shipped in a -devel package of
the app which owns the schema definition, but polkit does not do this.
Thus libvirt (and other apps) must ship their own local 'its' rules for
polkit.

Reviewed-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

po/its/polkit.its

@@ -0,0 +1,8 @@
+<?xml version="1.0"?>
+<its:rules xmlns:its="http://www.w3.org/2005/11/its"
+           version="2.0">
+  <its:translateRule selector="//*" translate="no"/>
+  <its:translateRule selector="//action/description |
+                               //action/message"
+                     translate="yes"/>
+</its:rules>

po/its/polkit.loc

@@ -0,0 +1,6 @@
+<?xml version="1.0"?>
+<locatingRules>
+  <locatingRule name="polkit policy" pattern="*.policy">
+    <documentRule localName="policyconfig" target="polkit.its"/>
+  </locatingRule>
+</locatingRules>

po/meson.build

@@ -14,6 +14,7 @@ i18n.gettext(
     '--package-version=@0@'.format(meson.project_version()),
     '--sort-output',
   ],
+  data_dirs: meson.current_source_dir()
 )
 
 potfiles_dep = [