pgsql: Remove useless code

Remove useless code

BuildDescForRelation() goes out of its way to fill in
->constr->has_not_null, but that value is not used for anything later,
so this code can all be removed.  Note that BuildDescForRelation()
doesn't make any effort to fill in the rest of ->constr, so there is
no claim that that structure is completely filled in.

Reviewed-by: Tomasz Rybak <tomasz.rybak@post.pl>
Discussion: https://www.postgresql.org/message-id/flat/a368248e-69e4-40be-9c07-6c3b5880b0a6@eisentraut.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e26d313bad92e71e2b59cc2e81870bf6d750de1f

Modified Files
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src/backend/commands/tablecmds.c | 25 +++----------------------
1 file changed, 3 insertions(+), 22 deletions(-)