Removed LZTEXT datatype as discussed.

src/backend/utils/adt/Makefile

src/backend/utils/adt/lztext.c

src/backend/utils/cache/relcache.c

src/include/catalog/pg_amop.h

src/include/catalog/pg_amproc.h

src/include/catalog/pg_opclass.h

src/include/catalog/pg_operator.h

src/include/catalog/pg_proc.h

src/include/catalog/pg_rewrite.h

src/include/catalog/pg_type.h

src/include/utils/builtins.h

src/include/utils/lztext.h