pgsql: Push attidentity and attgenerated handling into BuildDescForRela

Push attidentity and attgenerated handling into BuildDescForRelation()

Previously, this was handled by the callers separately, but it can be
trivially moved into BuildDescForRelation() so that it is handled in a
central place.

Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da@eisentraut.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/6d341407a6e34cd6857cf55ee4757397286542db

Modified Files
--------------
src/backend/access/common/tupdesc.c | 2 ++
src/backend/commands/tablecmds.c    | 2 --
2 files changed, 2 insertions(+), 2 deletions(-)