Make it possible for the initiator side to operate in both proxy
and normal mode; this makes it possible to compile with the former
by default, but use it only when neccessary.  That's especially
important for the userland part.

Sponsored by:	The FreeBSD Foundation
Fix VIRTUAL and PROF interval timers for short intervals, broken at r247903.

Due to the way those timers are implemented, we can't handle very short
intervals.  In addition to that mentioned patch caused math overflows
for short intervals.  To avoid that round those intervals to 1 tick.

PR:		kern/187668
MFC after:	1 week