Deprecate ColorButton, ColorChooser, ColorChooserDialog,
FileChooser, FileChooserDialog, FileChooserNative, FileChooserWidget,
FontButton, FontChooser, FontChooserDialog, FontChooserWidget,
MessageDialog, TreeModelColumn, TreeModelColumnRecord

The corresponding API in GTK has been deprecated.

Demo programs still use deprecated API. It's not possible to build
the demo programs with build-deprecated-api=false.