Because it is very hard to make fork(2) from threaded process safe (we are

Because it is very hard to make fork(2) from threaded process safe (we are
limited to async-signal safe functions in the child process), move all hooks
execution to the main (non-threaded) process.

Do it by maintaining connection (socketpair) between child and parent
and sending events from the child to parent, so it can execute the hook.

This is step in right direction for others reasons too. For example there is
one less problem to drop privs in worker processes.

MFC after:	2 weeks
Obtained from:	Wheel Systems Sp. z o.o. http://www.wheelsystems.com