pidgin/pidgin

Convert the gplugin subproject to use the auto fallback stuff of dependency.

Testing Done:
Verified the the purples gir's loaded and were able to call into gplugin under python, when built as a subproject and against a system installed version.

Reviewed at https://reviews.imfreedom.org/r/937/
<?xml version="1.0" encoding="UTF-8"?>
<glade-catalog name="pidgin" version="@PURPLE_MAJOR_VERSION@.@PURPLE_MINOR_VERSION@" library="pidgin3">
<glade-widget-classes>
<glade-widget-class name="PidginAccountChooser" generic-name="account_chooser" title="AccountChooser"/>
<glade-widget-class name="PidginAccountsMenu" generic-name="accounts_menu" title="AccountsMenu"/>
<glade-widget-class name="PidginAccountStore" generic-name="account_store" title="AccountStore"/>
<glade-widget-class name="PidginAccountFilterConnected" generic-name="account_filter_connected" title="FilterConnected"/>
<glade-widget-class name="PidginAccountFilterProtocol" generic-name="account_filter_protocol" title="FilterProtocol"/>
<glade-widget-class name="PidginAvatar" generic-name="avatar" title="Avatar"/>
<glade-widget-class name="PidginCloseButton" generic-name="close-button" title="CloseButton"/>
<glade-widget-class name="PidginConversationWindow" generic-name="conversation_window" title="ConversationWindow"/>
<glade-widget-class name="PidginCredentialProviderRow" generic-name="credential_provider_row" title="CredentialProviderRow"/>
<glade-widget-class name="PidginCredentialsPage" generic-name="credentials_page" title="CredentialsPage"/>
<glade-widget-class name="PidginDialog" generic-name="dialog" title="Dialog"/>
<glade-widget-class name="PidginInviteDialog" generic-name="invite_dialog" title="InviteDialog"/>
<glade-widget-class name="PidginMenuTray" generic-name="menu_tray" title="MenuTray"/>
<glade-widget-class name="PidginPluginsMenu" generic-name="plugins_menu" title="PluginsMenu"/>
<glade-widget-class name="PidginPresenceIcon" generic-name="presence_icon" title="PresenceIcon"/>
<glade-widget-class name="PidginProtocolChooser" generic-name="protocol_chooser" title="ProtocolChooser"/>
<glade-widget-class name="PidginProtocolStore" generic-name="protocol_store" title="ProtocolStore"/>
<glade-widget-class name="PidginScrollBook" generic-name="scroll_book" title="ScrollBook"/>
<glade-widget-class name="PidginStatusBox" generic-name="status_box" title="StatusBox"/>
</glade-widget-classes>
<glade-widget-group name="pidgin" title="Pidgin">
<glade-widget-class-ref name="PidginAccountChooser"/>
<glade-widget-class-ref name="PidginAccountsMenu"/>
<glade-widget-class-ref name="PidginAccountStore"/>
<glade-widget-class-ref name="PidginAccountFilterConnected"/>
<glade-widget-class-ref name="PidginAccountFilterProtocol"/>
<glade-widget-class-ref name="PidginAvatar"/>
<glade-widget-class-ref name="PidginCloseButton"/>
<glade-widget-class-ref name="PidginConversationWindow"/>
<glade-widget-class-ref name="PidginCredentialProviderRow"/>
<glade-widget-class-ref name="PidginCredentialsPage"/>
<glade-widget-class-ref name="PidginDialog"/>
<glade-widget-class-ref name="PidginInviteDialog"/>
<glade-widget-class-ref name="PidginMenuTray"/>
<glade-widget-class-ref name="PidginPluginsMenu"/>
<glade-widget-class-ref name="PidginPresenceIcon"/>
<glade-widget-class-ref name="PidginProtocolChooser"/>
<glade-widget-class-ref name="PidginProtocolStore"/>
<glade-widget-class-ref name="PidginScrollBook"/>
<glade-widget-class-ref name="PidginStatusBox"/>
</glade-widget-group>
</glade-catalog>