ignore intermittent differences in the "predefined minimum record" flag.

page_zip_validate_low(): Renamed from page_zip_validate(), with an
additional parameter: ibool sloppy.  Ignore REC_INFO_MIN_REC_FLAG when
sloppy == TRUE.

page_zip_validate(): Wrapper for page_zip_validate_low().  Pass
sloppy = recv_recovery_is_on().

recv_recover_page(): After applying the changes from the redo log to a
compressed B-tree page, invoke page_zip_validate_low() in strict mode.