plugin-manager,plugin: run pre-probing filters early

For each port, we will construct the list of plugins to test with. In that list
we will include those plugins which are likely to handle a given port, so we
will skip all those which aren't.

To see if a plugin is likely or not, we will run the pre-probing filters before
adding them to the list, with the new `mm_plugin_discard_port_early()'. This
method will return one of these hints:

 * UNSUPPORTED: The plugin will not be able to handle this port.
 * MAYBE: The plugin may handle this port.
 * LIKELY: The plugin may (very likely) handle this port.
 * SUPPORTED: If any plugin should support the port, this is it.

Plugins reported to be 'likely' supporting the port will be probed before the
ones reported just as 'maybe'.

If a plugin reports 'supported' only that one and the fallback generic ones will
be tried.

src/mm-plugin.h

@@ -67,6 +67,13 @@ typedef enum {
     MM_PLUGIN_SUPPORTS_PORT_SUPPORTED
 } MMPluginSupportsResult;
 
+typedef enum {
+    MM_PLUGIN_SUPPORTS_HINT_UNSUPPORTED,
+    MM_PLUGIN_SUPPORTS_HINT_MAYBE,
+    MM_PLUGIN_SUPPORTS_HINT_LIKELY,
+    MM_PLUGIN_SUPPORTS_HINT_SUPPORTED,
+} MMPluginSupportsHint;
+
 typedef struct _MMPlugin MMPlugin;
 typedef struct _MMPluginClass MMPluginClass;
 typedef struct _MMPluginPrivate MMPluginPrivate;
@@ -102,8 +109,12 @@ struct _MMPluginClass {
 GType mm_plugin_get_type (void);
 
 const gchar *mm_plugin_get_name (MMPlugin *plugin);
-gint         mm_plugin_cmp      (const MMPlugin *plugin_a,
-                                 const MMPlugin *plugin_b);
+
+/* This method will run all pre-probing filters, to see if we can discard this
+ * plugin from the probing logic as soon as possible. */
+MMPluginSupportsHint mm_plugin_discard_port_early (MMPlugin *plugin,
+                                                   MMDevice *device,
+                                                   GUdevDevice *port);
 
 void                   mm_plugin_supports_port        (MMPlugin *plugin,
                                                        MMDevice *device,