Add ‘gsettings list-schemas --print-paths’ option

Prints next to the name of non-relocatable schemas their paths.

https://bugzilla.gnome.org/show_bug.cgi?id=792064

docs/reference/gio/gsettings.xml

@@ -75,6 +75,7 @@
   <cmdsynopsis>
     <command>gsettings</command>
     <arg choice="plain">list-schemas</arg>
+    <arg choice="opt">--print-paths</arg>
   </cmdsynopsis>
   <cmdsynopsis>
     <command>gsettings</command>
@@ -198,7 +199,8 @@ Reset all keys under the given <replaceable>SCHEMA</replaceable>.
 <listitem><para>
 Lists the installed, non-relocatable schemas.
 See <option>list-relocatable-schemas</option> if you are interested in
-relocatable schemas.
+relocatable schemas. If <optional><option>--print-paths</option></optional>
+is given, the path where each schema is mapped is also printed.
 </para></listitem>
 </varlistentry>