Create alias when a pure objc #setFoo method is overriden

[eloy.de.enige@…]

When the user, in Ruby, overrides a #setFoo method of a pure objc superclass, MacRuby should create an alias from #foo= to the new #setFoo method.

This is because the MacRuby helper which delegates #foo= to #setFoo only does that for pure objc #setFoo method implementations.

class YourView < NSView
  def setFrame(frame)
    super
    # custom stuff
  end

  # MacRuby should create this alias when #setFrame was defined above.
  alias_method :frame=, :setFrame
end

[eloy.de.enige@…]

Fixed in #3919.