pgsql: In psql, avoid leaking a PGresult after a query is cancelled.

In psql, avoid leaking a PGresult after a query is cancelled.

After a query cancel, the tail end of ExecQueryAndProcessResults
took care to clear any not-yet-read PGresults; but it forgot about
the one it has already read. There would only be such a result
when handling a multi-command string made with "\;", so that you'd
have to cancel an earlier command in such a string to reach the
bug at all. Even then, there would only be leakage of a single
PGresult per cancel, so it's not surprising nobody noticed this.
But a leak is a leak.

Noted while re-reviewing 90f517821, but this is independent of that:
it dates to 7844c9918. Back-patch to v15 where that came in.

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4f1d33d707fbdf38296ed8b262ae1ea3dcde2b18

Modified Files
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src/bin/psql/common.c | 2 ++
1 file changed, 2 insertions(+)