This allows the contents of the current FreeBSD VT console to be accessed
by vtspeakd(1) for example. The API is defined by the following sysctls:
kern.vt.screen_reader.feed
kern.vt.screen_reader.text_utf8
kern.vt.screen_reader.col
kern.vt.screen_reader.row
kern.vt.screen_reader.lines
kern.vt.screen_reader.hangup_pid
MFC after: 1 week
Sponsored by: NVIDIA Networking