Revision 208612

Fixes from NetBSD for nvi visual mode:

- Fix handling of ^@ when reading an ex command. Don't try to replay
  the previous input.
- Fix handling of ^C in insert mode and when reading an ex command.
  Repeating an interrupted input could cause a crash and interrupting
  ex command input could cause a file corruption.
- Fix a bug which causes crashes in file name completion when a file
  name is longer than the screen width.
- When an error occurs in v_txt(), leave the input mode.

PR:		bin/21089, bin/136393
Obtained from:	NetBSD