[master] Merge branch 'trac5343' (dead code removal)

# Conflicts:
#	src/bin/dhcp6/json_config_parser.cc

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

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

diff --cc src/lib/dhcpsrv/parsers/dhcp_parsers.cc
Simple merge

diff --cc src/lib/dhcpsrv/parsers/dhcp_parsers.h
Simple merge

diff --cc src/lib/dhcpsrv/tests/dhcp_parsers_unittest.cc
Simple merge