pgsql: Fix use-after-free in ri_LoadConstraintInfo

Fix use-after-free in ri_LoadConstraintInfo

conindid was read from conForm after ReleaseSysCache(tup).  Move
the read to before the release.

Introduced by commit 2da86c1ef9b5.

Per buildfarm member prion.

Discussion: https://postgr.es/m/CA+HiwqGGYjN6F2oL7yAk=hvSs-sj3TPqZ9JC9iyLkCqJadECrw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/68a8601ee9ec7285b5a3839e17360c0a9d0e52a3

Modified Files
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src/backend/utils/adt/ri_triggers.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)