(ITS#7337) libmdb can corrupt when reaching maxsize

[hyc@OpenLDAP.org]

Full_Name: Howard Chu
Version: HEAD/RE24
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (37.19.97.21)
Submitted by: hyc


Already fixed by commit 234cd9dfb54ef2f7f83963d95b6eb8e9735bb372

If the DB maxsize was reached while pruning consumed records from the free list
inside mdb_txn_commit, the error was ignored. As a result the txn_commit would
return success even though it only partly succeeded.

 The code is now fixed to abort the txn and return the error code.