Fix Bug#43660 SHOW INDEXES/ANALYZE does NOT update cardinality for indexes
of InnoDB table

by replacing the PRNG that is used to pick random pages with a better
one.

This is based on r4670 but also adds a new configuration option and
enables the fix only if this option is changed. Please skip the present
revision when merging.

Approved by:	Heikki (via email)