Created attachment 187480 [details] [review]
Add support for unions inside boxed types

The attached patch adds support for GIRs with the definitions like the following:

    <record name="ContactPhoto"
            c:type="EContactPhoto"
            glib:type-name="EContactPhoto"
            glib:get-type="e_contact_photo_get_type"
            c:symbol-prefix="contact_photo">
      <union name="data" c:type="data">
        <record name="inlined" c:type="inlined">
          <field name="mime_type" writable="1">
            <type name="utf8" c:type="gchar*"/>
          </field>
          <field name="length" writable="1">
            <type name="gsize" c:type="gsize"/>
          </field>
          <field name="data" writable="1">
            <type name="guint8" c:type="guchar*"/>
          </field>
        </record>
        <field name="uri" writable="1">
          <type name="utf8" c:type="gchar*"/>
        </field>
      </union>
    </record>

(unions inside boxed types).