pgsql: pageinspect: Fix relcache leak in gist_page_items().

pageinspect: Fix relcache leak in gist_page_items().

The gist_page_items() function opened the index relation on first call and
closed it on the last call. But there's no guarantee that the function is
run to completion, leading to a relcache leak and warning at the end of
the transaction. To fix, refactor the function to return all the rows in
one call, as a tuplestore.

Reported-by: Tom Lane
Discussion: https://www.postgresql.org/message-id/234863.1610916631%40sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/04eb75e783ba49ca2e0e75088d6590b64be8ed4d

Modified Files
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contrib/pageinspect/gistfuncs.c | 170 +++++++++++++++++-----------------------
1 file changed, 74 insertions(+), 96 deletions(-)