The Informix sqlpack rendered an INTEGER8 column type as the literal
string "INTEGER8" - the internal token name, not a SQL type. Every
neighbouring rule emits the real spelling (SERIAL8 gives "SERIAL8"),
so this one was the odd one out.
The server rejected the resulting DDL with -9628 "Type (integer8) not
found", which made BIGINT and INT8 unusable in CREATE TABLE and in any
other statement naming the type, a cast included.
Now emits INT8: accepted by every Informix version where the type
exists (BIGINT needs 11.x), and matching the DTYPE_INT8 the runtime
already uses for these columns. Also records the DDL_INT8 feature
marker, as the surrounding types do.
