pgsql: Fix temporary memory leak in system table index scans

Fix temporary memory leak in system table index scans

Commit 811af9786b introduced palloc() calls into systable_beginscan()
and systable_beginscan_ordered(). But there was no pfree(), as is the
usual style.

It turns out that an ANALYZE of a partitioned table can invoke many
thousand system table index scans, and this memory is not cleaned up
until the end of the command, so this can temporarily leak quite a bit
of memory. Maybe there are improvements to be made at a higher level
about this, but for now, insert a couple of corresponding pfree()
calls to fix this particular issue.

Reported-by: Justin Pryzby <pryzby(at)telsasoft(dot)com>
Discussion: https://www.postgresql.org/message-id/Z0XTfIq5xUtbkiIh@pryzbyj2023

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1acf10549e64c6a52ced570d712fcba1a2f5d1ec

Modified Files
--------------
src/backend/access/index/genam.c | 4 ++++
1 file changed, 4 insertions(+)