pgsql-server: Tweak prettyprinting rules for saner indenting of UNION,

Log Message:
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Tweak prettyprinting rules for saner indenting of UNION, INTERSECT,
EXCEPT constructs.

Modified Files:
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pgsql-server/src/backend/utils/adt:
ruleutils.c (r1.179 -> r1.180)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/utils/adt/ruleutils.c.diff?r1=1.179&r2=1.180)