pgsql: Fix pg_dump to dump casts between auto-generated types.

Fix pg_dump to dump casts between auto-generated types.

The heuristic for when to dump a cast failed for a cast between table
rowtypes, as reported by Frédéric Rejol. Fix it by setting
the "dump" flag for such a type the same way as the flag is set for the
underlying table or base type. This won't result in the auto-generated
type appearing in the output, since setting its objType to DO_DUMMY_TYPE
unconditionally suppresses that. But it will result in dumpCast doing what
was intended.

Back-patch to 8.3. The 8.2 code is rather different in this area, and it
doesn't seem worth any risk to fix a corner case that nobody has stumbled
on before.

Branch
------
REL8_4_STABLE

Details
-------
http://git.postgresql.org/pg/commitdiff/58625e48a3fdfd64b0f8b9297c36d824a3ce8327

Modified Files
--------------
src/bin/pg_dump/common.c | 2 +-
src/bin/pg_dump/pg_dump.c | 26 ++++++++++++++++++++------
2 files changed, 21 insertions(+), 7 deletions(-)