inotify: fix segfault on watching hard links

The call to _start() fills in the dirname, basename, and filename
arguments according to the following rules:

  dir watches: dirname filled

  file watches: dirname and basename filled

  hardlink: filename filled

This doesn't map to how the current inotify backend works very nicely,
so we need to adjust things a bit when creating our "sub" objects.

https://bugzilla.gnome.org/show_bug.cgi?id=755721

gio/inotify/inotify-sub.h

@@ -33,8 +33,8 @@ typedef struct
 } inotify_sub;
 
 inotify_sub *_ih_sub_new (const gchar  *dirname,
+			  const gchar  *basename,
 			  const gchar  *filename,
-			  gboolean      watch_hardlinks,
 			  gpointer      user_data);
 void         _ih_sub_free (inotify_sub *sub);