pgsql: Fix portability issue in new jsonbsubs code.

Fix portability issue in new jsonbsubs code.

On machines where sizeof(Datum) > sizeof(Oid) (that is, any 64-bit
platform), the previous coding would compute a misaligned
workspace->index pointer if nupper is odd. Architectures where
misaligned access is a hard no-no would then fail. This appears
to explain why thorntail is unhappy but other buildfarm members
are not.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7c5d57caed4d8af705d0cc3131d0d8ed72b7a41d

Modified Files
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src/backend/utils/adt/jsonbsubs.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)