Fix memleak in avatar_chooser_update_preview_cb. Free string returned by gtk_file_chooser_get_preview_filename.
Fix memleak in avatar_chooser_update_preview_cb. Free string returned by
gtk_file_chooser_get_preview_filename.

Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,Distrotech/telepathy-account-widgets,GNOME/telepathy-account-widgets,GNOME/telepathy-account-widgets