Thread: pgsql: Improve page split in rtree emulation.

Log Message:
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Improve page split in rtree emulation. Now if splitted result has
big misalignement, then it tries to split page basing on distribution
of boxe's centers.

Per report from  Dolafi, Tom <dolafit@janelia.hhmi.org>

 Backpatch is needed, change doesn't affect on-disk storage.

Modified Files:
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    pgsql/src/backend/access/gist:
        gistproc.c (r1.10 -> r1.11)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/gist/gistproc.c?r1=1.10&r2=1.11)