(ITS#7620) LMDB overflow page management

[hyc@OpenLDAP.org]

Full_Name: Howard Chu
Version: 2.4.35
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (78.155.233.73)
Submitted by: hyc


Pages that are dirtied get pulled out of the freeDB. If they are freed in the
same txn they should be returned to their original place in the freeDB instead
of joining the current txn's list of freed pages. This is particularly important
for overflow pages because otherwise we can consume a lot of overflow pages
rapidly in some cases.

Commit e7f6767ea815fe0ada1f95037dfdec176ec4d5bb in mdb.master is for this issue,
but it needs additional fixes.