Roxiemem refactoring - clean up code and comments
Roxiemem refactoring - clean up code and comments

- Fix minor issue with leak check
- Improve comments about ABA issue
- Add a CAS test - not effective against current code

Signed-off-by: Gavin Halliday <2edfa8aca9fb78974188e5b35be8b52d4e4967ae@lexisnexis.com>

afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform,afishbeck/HPCC-Platform