pgsql: Defend against null scankeys in spgist searches.

Defend against null scankeys in spgist searches.

Should've thought of that one earlier.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/b7a0e8fb4d6fafcd30555e4ddf18e77e138ec3d0

Modified Files
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src/backend/access/spgist/spgscan.c | 30 ++++++++++++++++++++++++------
1 files changed, 24 insertions(+), 6 deletions(-)