Fixed: windows that were autoresized and not constrainable would obey the global CPWindowConstrainToScreen flag.

Previously, if a window had an autoresizingMask and was marked as not being constrained (for example _CPMenuBarWindow), and the CPWindowConstrainToScreen was set to NO, resizing the platform window would not autoresize the window.

This commit ensures that windows that autoresize but don't care about constraining will resize with the platform window no matter what.

Fixes #1981.