Replace some strncpy() by strlcpy().

contrib/chkpass/chkpass.c

contrib/dblink/dblink.c

src/backend/libpq/be-secure.c

src/backend/utils/fmgr/dfmgr.c

src/backend/utils/misc/guc.c

src/bin/psql/tab-complete.c

src/interfaces/ecpg/preproc/descriptor.c

src/test/regress/pg_regress.c