Someone complained that their keyboard-interactive password prompt was being

Someone complained that their keyboard-interactive password prompt was being
truncated - it was from OpenSSH on HP/UX and had all sorts of stuff in it
("last successful login" etc).

Bodged it by bumping up the space allocated in the fixed array for a password
prompt. Also added an indication that the prompt is being truncated, as
required by draft-ietf-secsh-auth-kbdinteract-06.

(NB that before this checkin, there was a more-or-less harmless buffer overread
where if we ever received a keyboard-interactive prompt with echo=1, we'd
probably spew goo on the terminal; fixed now.)

[originally from svn r4476]