[master] subnet_id column types now consistent in schemas

    Merges in branch 'trac5522'

diff --cc configure.ac
Simple merge

diff --cc src/share/database/scripts/mysql/dhcpdb_create.mysql
Simple merge

diff --cc src/share/database/scripts/mysql/upgrade_5.2_to_6.0.sh.in
Simple merge

diff --cc src/share/database/scripts/pgsql/dhcpdb_create.pgsql
Simple merge

diff --cc src/share/database/scripts/pgsql/upgrade_3.3_to_4.0.sh.in
Simple merge