Write protect base page after superpage demotion so that it may repromote
Write protect base page after superpage demotion so that it may repromote

When clearing the modification status of the superpage, one of the
base pages produced during demotion should be marked as write disabled.
The intention is that subsequent write access may repromote.
In the current implementation this was done wrong as write permission was
granted instead of forbidden.

Approved by:	cognet (mentor)
Approved by:	re

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