pgsql: Fix dumping of casts and transforms using built-in functions

Fix dumping of casts and transforms using built-in functions

In pg_dump.c dumpCast() and dumpTransform(), we would happily ignore the
cast or transform if it happened to use a built-in function because we
weren't including the information about built-in functions when querying
pg_proc from getFuncs().

Modify the query in getFuncs() to also gather information about
functions which are used by user-defined casts and transforms (where
"user-defined" means "has an OID >= FirstNormalObjectId"). This also
adds to the TAP regression tests for 9.6 and master to cover these
types of objects.

Back-patch all the way for casts, back to 9.5 for transforms.

Discussion: https://www.postgresql.org/message-id/flat/20160504183952.GE10850%40tamriel.snowman.net

Branch
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REL9_6_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/542975a147525caa659ac08220b81c32a60f0a5c

Modified Files
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src/bin/pg_dump/pg_dump.c | 46 +++++++++++++++++-----
src/bin/pg_dump/t/002_pg_dump.pl | 82 +++++++++++++++++++++++++---------------
2 files changed, 88 insertions(+), 40 deletions(-)