pgsql: Release PQconninfoOptions array in GetDbnameFromConnectionOption

Release PQconninfoOptions array in GetDbnameFromConnectionOptions().

It wasn't getting freed in one code path, which Coverity identified as
a resource leak. It's probably of little consequence, but re-ordering
the code into the correct sequence is no more work than dismissing the
complaint. Minor oversight in commit a145f424d.

While here, improve the unreasonably clunky coding of
FindDbnameInConnParams: use of an output parameter is unnecessary
and prone to uninitialized-variable problems.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d37e0d0c50ee560fa2e7dc2a4dc904a885957985

Modified Files
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src/bin/pg_basebackup/streamutil.c | 29 ++++++++++++++---------------
1 file changed, 14 insertions(+), 15 deletions(-)