pgsql: Only issue LOCK TABLE commands when necessary

Only issue LOCK TABLE commands when necessary

Reviewing the cases where we need to LOCK a given table during a dump,
it was pointed out by Tom that we really don't need to LOCK a table if
we are only looking to dump the ACL for it, or certain other
components. After reviewing the queries run for all of the component
pieces, a list of components were determined to not require LOCK'ing
of the table.

This implements a check to avoid LOCK'ing those tables.

Initial complaint from Rushabh Lathia, discussed with Robert and Tom,
the patch is mine.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/e1b120a8cbb0f39a79926fd173f33e57202cdfa0

Modified Files
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src/bin/pg_dump/pg_dump.c | 5 ++++-
src/bin/pg_dump/pg_dump.h | 27 +++++++++++++++++++++++++++
2 files changed, 31 insertions(+), 1 deletion(-)