evdev: Add touchscreen mouse emulation and pressure support (thanks, Zach!).

This also solves reports of this log message:

"INFO: The key you just pressed is not recognized by SDL. To help get this
fixed, please report this to the SDL forums/mailing list
<https://discourse.libsdl.org/> EVDEV KeyCode 330"

(EVDEV KeyCode 330 is BTN_TOUCH.)

Fixes Bugzilla #4147.
1 file changed