Description of problem:
In cn=monitor bytessent and possibly other values (like entriessent, opsinitiated, opscompleted) are overflowing at 2^32-1.

Version-Release number of selected component (if applicable):
389-ds-base-1.3.5.10-11.el7

How reproducible:
always

Steps to Reproduce:
1. Add 100k entries
2. Search for all entries
3. Check value of bytessent in cn=monitor
4. Repeat steps 2-3 

Actual results:
After some time bytessent passes 2^32-1 boundary and starts from 0

Expected results:
Max value of bytessent is expected to be 2^64-1.

Additional info:
389-ds-base-1.2.11 is not affected.