IPv6 cleanups.

config/c-library.m4

configure

configure.in

src/backend/libpq/auth.c

src/backend/libpq/hba.c

src/backend/libpq/ip.c

src/backend/libpq/pg_hba.conf.sample

src/backend/libpq/pqcomm.c

src/backend/postmaster/pgstat.c

src/backend/postmaster/postmaster.c

src/include/getaddrinfo.h

src/include/libpq/ip.h

src/include/libpq/libpq.h

src/include/libpq/pqcomm.h

src/include/pg_config.h.in

src/include/pg_config_manual.h

src/include/port/bsdi.h

src/interfaces/libpq/fe-connect.c

src/interfaces/libpq/libpq-int.h

src/port/getaddrinfo.c