(ITS#8801) Fix pending CSN queue

[hyc@openldap.org]

Full_Name: Howard Chu
Version: 2.4
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (83.136.45.75)
Submitted by: hyc


The CSN queue tracks in-progress write operations. It uses connID and opID to
identify a CSN queue entry that corresponds to a given operation. This is
error-prone in the case of syncrepl, which always uses the same connID and opID
for all of its internal operations. Should just use the Operation pointer, which
is always unique and unambiguous.