amount of bytes (supposed to be) written by vsnprintf exceeds the
size of the buffer.
PR: bin/48844
Submitted by: Peter A Jonsson <pj@ludd.luth.se>
Obtained from: OpenBSD
MFC after: 1 month
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.