Redundant protocol conformance warnings

[rhx]

Currently gir2swift just blindly translates .gir file interface implementations into protocol conformances, leading to redundant conformance warnings, e.g.:

Gtk-3.0-TearoffMenuItem-UIManager.swift:25726:128: warning: redundant conformance constraint 'Self': 'TreeModelProtocol'
public protocol TreeStoreProtocol: GLibObject.ObjectProtocol, BuildableProtocol, TreeDragDestProtocol, TreeDragSourceProtocol, TreeModelProtocol, TreeSortableProtocol {
                                                                                                                               ^
Gtk-3.0-TearoffMenuItem-UIManager.swift:25726:147: note: conformance constraint 'Self': 'TreeModelProtocol' implied here
public protocol TreeStoreProtocol: GLibObject.ObjectProtocol, BuildableProtocol, TreeDragDestProtocol, TreeDragSourceProtocol, TreeModelProtocol, TreeSortableProtocol {