This adds specific marshallers for all of the locations where a generic
marshaller is being used. It also provides va_marshallers to reduce the
chances that we get stack traces from perf going through ffi_call_unix64.
This is forward ported from gtk-3-24.
# Conflicts:
# gtk/gtkeventcontrollerkey.c
# gtk/gtkeventcontrollermotion.c
# gtk/gtkgesture.c
# gtk/gtkgesturemultipress.c
The idea is that GTK+ 4 will be an epoch, API-wise.
Everything that was around for 4.0 has been there
since the beginning of the epoch and doesn't need
markers.
This is a GtkGesture done to deal with stylus events from drawing tablets.
Those have a special number of characteristics that extend a regular
pointer, so it makes sense to wrap that.
