pgsql: Fix pg_dump to dump shell types.

Fix pg_dump to dump shell types.

Per discussion, it really ought to do this. The original choice to
exclude shell types was probably made in the dark ages before we made
it harder to accidentally create shell types; but that was in 7.3.

Also, cause the standard regression tests to leave a shell type behind,
for convenience in testing the case in pg_dump and pg_upgrade.

Back-patch to all supported branches.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/3bdd7f90fc0a038ee8b5b3fd9f9507cf2f07a4b2

Modified Files
--------------
src/bin/pg_dump/pg_dump.c | 77 ++++++++++++++++++++++++++---
src/bin/pg_dump/pg_dump.h | 2 +-
src/test/regress/expected/create_type.out | 2 +
src/test/regress/sql/create_type.sql | 3 ++
4 files changed, 77 insertions(+), 7 deletions(-)