pgsql: Avoid infinite recursion when dumping new planner

Log Message:
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Avoid infinite recursion when dumping new planner EquivalenceClass trees.

Modified Files:
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pgsql/src/backend/nodes:
outfuncs.c (r1.296 -> r1.297)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/outfuncs.c.diff?r1=1.296&r2=1.297)