pgsql: Teach pg_dump to dump comments on RLS policy objects.

Teach pg_dump to dump comments on RLS policy objects.

This was unaccountably omitted in the original RLS patch.
The SQL syntax is basically the same as for comments on triggers,
so crib code from dumpTrigger().

Per report from Marc Munro.  Back-patch to all supported branches.

Discussion: https://postgr.es/m/1581889298.18009.15.camel@bloodnok.com

Branch
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REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/bd2cd138f9bbaea99f8d632914c33ae5103afa6c

Modified Files
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src/bin/pg_dump/pg_dump.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)