Ticket #47409 - allow setting db deadlock rejection policy

https://fedorahosted.org/389/ticket/47409
Reviewed by: nhosoi (Thanks!)
Branch: 389-ds-base-1.2.11
Fix Description: Fix coverity CID 11893 (#1 of 1): Unsigned compared against 0 (NO_EFFECT)
val is u_int32_t which is never less than 0
Platforms tested: RHEL6 x86_64
Flag Day: no
Doc impact: yes - document new config parameter
(cherry picked from commit 989a30bb2d63ee6b9157a9eb6a3d2ff6828abc60)
(cherry picked from commit 75b9e42a6555073d902526c20a606d17fd11f967)
(cherry picked from commit 1baa10dd3c14c6cdc29aae5d114547df812b5c17)