glib-compile-resources: Add a --version option

There have been some improvements to the tool recently, but it's hard to
know if those are available on a given system unless the tool provides a
--version commandline option.

https://bugzilla.gnome.org/show_bug.cgi?id=772269

docs/reference/gio/glib-compile-resources.xml

@@ -56,6 +56,13 @@ Print help and exit
 </para></listitem>
 </varlistentry>
 
+<varlistentry>
+<term><option>--version</option></term>
+<listitem><para>
+Print program version and exit
+</para></listitem>
+</varlistentry>
+
 <varlistentry>
 <term><option>--target=<replaceable>TARGET</replaceable></option></term>
 <listitem><para>