Required catalog changes for extended LONG attribute storage.

src/backend/access/common/tupdesc.c

src/backend/bootstrap/bootstrap.c

src/backend/catalog/heap.c

src/backend/catalog/index.c

src/backend/commands/command.c

src/backend/executor/execUtils.c

src/include/catalog/pg_attribute.h

src/include/catalog/pg_class.h