[master] Merge branch 'trac3062'

Corrects a bug in Hooks code that was improperly
creating a new callout handle on every call, rather
than maintaining it throughout the context of the
packet being processed.

diff --cc src/bin/dhcp4/dhcp4_srv.cc
Simple merge

diff --cc src/bin/dhcp6/dhcp6_srv.cc
Simple merge

diff --cc src/bin/dhcp6/dhcp6_srv.h
Simple merge

diff --cc src/lib/dhcpsrv/Makefile.am
Simple merge

diff --cc src/lib/dhcpsrv/tests/Makefile.am
Simple merge