Rule flag in gram.y

There is some code in gram.y that detects whether you are in a RULE so
NEW/OLD can be detected. Seems the value is reset on parser start and
set on RULE start, but not reset on rule and. A multi-query string
could use NEW/OLD in the queries after the RULE even though they are
invalid. The following patch fixes this by resetting the flag when the
rule action happens.

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Bruce Momjian | http://candle.pha.pa.us
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