pgsql: Fix hash_array

Fix hash_array

Commit a3d2b1bbe904b0ca8d9fdde20f25295ff3e21f79 neglected to
initialize the type_id field of the synthesized type cache entry, so
it would make a new one on every call.

Also, better use the per-function memory context for this; otherwise
it leaks memory.

Discussion: https://www.postgresql.org/message-id/flat/17158-8a2ba823982537a4%40postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/851ff9335742d22a3cb1a5ab789208e4ee01dcef

Modified Files
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src/backend/utils/adt/arrayfuncs.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)