upstream commit

Prefer setvbuf() to setlinebuf() for portability; ok
 deraadt@
upstream commit

convert KRL code to new buffer API

ok markus@
upstream commit

add RevokedHostKeys option for the client

Allow textfile or KRL-based revocation of hostkeys.
upstream commit

key_in_file() wrapper is no longer used
upstream commit

Nuke yet more obvious #include duplications.

ok deraadt@
upstream commit

add tests for new client RevokedHostKeys option; refactor
 to make it a bit more readable