The `ascii` member was only kept for historic reason as some platforms
didn't support utf8 when it was first introduced.
Remove the `ascii` struct members since many checks used this as a
fall-back for utf8_buf not being set which isn't needed.
There are a few cases where it's convenient to access the ASCII value
of an event (or nil) so a function has been added to do that.
*Details*
- WM_event_utf8_to_ascii() has been added for the few cases an events
ASCII value needs to be accessed, this just avoids having to do
multi-byte character checks in-line.
- RNA Event.ascii remains, using utf8_buf[0] for single byte characters.
- GHOST_TEventKeyData.ascii has been removed.
- To avoid regressions non-ASCII Latin1 characters from GHOST are
converted into multi-byte UTF8, when building X11 without
XInput & X_HAVE_UTF8_STRING it seems like could still occur.
d6fef73ef1