pgsql: Simplify cost_incremental_sort a bit

Simplify cost_incremental_sort a bit

Commit de0dc1a847 added code to cost_incremental_sort to handle varno 0.
Explicitly removing the RelabelType is not really necessary, because the
pull_varnos handles that just fine, which simplifies the code a bit.

Author: Richard Guo
Discussion: https://postgr.es/m/CAMbWs4_3_D2J5XxOuw68hvn0-gJsw9FXNSGcZka9aTymn9UJ8A%40mail.gmail.com
Discussion: https://postgr.es/m/20200411214639.GK2228%40telsasoft.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/60fbb4d762506c352c1af1229288a0753742cd95

Modified Files
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src/backend/optimizer/path/costsize.c | 12 +-----------
1 file changed, 1 insertion(+), 11 deletions(-)