MFC 272668:
Properly set the timeout in a query_state.  The global query_timeout
configuration value is an integer count of seconds, it is not a timeval.
Using memcpy() to copy a timeval from it put garbage into the tv_usec
field.

PR:		194025
MFC 268369,268817,272771,272772:
Rewrite timeout(9) to be callout(9)-centric instead.  Move the description
of timeout(9) to the end and mark it prominently as deprecated.  Document
somewhat how times are specified for the 'sbt' variants.  Better explain
how using callout_init_*() to associate a lock with a callout resolves
common races.