pgsql: postgres_fdw: Fix test for cached costs inestimate_path_cost_si

postgres_fdw: Fix test for cached costs in estimate_path_cost_size().

estimate_path_cost_size() failed to re-use cached costs when the cached
startup/total cost was 0, so it calculated the costs redundantly.

This is an oversight in commit aa09cd242f; but apply the patch to HEAD
only because there are no reports of actual trouble from that.

Author: Etsuro Fujita
Discussion: https://postgr.es/m/5C4AF3F3.4060409%40lab.ntt.co.jp

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/449d0a85507b07be3040df78a93e2966ed0908c8

Modified Files
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contrib/postgres_fdw/postgres_fdw.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)