pgsql: Rethink order of operations for dumping extension member objects

Rethink order of operations for dumping extension member objects.

My original idea of doing extension member identification during
getDependencies() didn't work correctly: we have to mark member tables as
not-to-be-dumped rather earlier than that, else their subsidiary objects
like indexes get dumped anyway. Rearrange code to mark them early enough.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/183d3cff850eee12357b8b4a8c5e62362ba5d8cc

Modified Files
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src/bin/pg_dump/common.c | 38 +++++---
src/bin/pg_dump/pg_dump.c | 236 +++++++++++++++++++++++++++++++--------------
src/bin/pg_dump/pg_dump.h | 4 +-
3 files changed, 190 insertions(+), 88 deletions(-)