RFR(M): 8212610: Fix handling of memory in PhaseIdealLoop::clone_loop_predicates()

[Roland Westrelin]

> One thing left is may be use r->find_edge(other_proj) instead of r->req()-1 in igvn->replace_input_of(phi,
> I known that rgn->add_req(if_uct); is used for new clone but I don't want any surprises if the edge is not last for some 
> reasons.

Here is a new webrev:

http://cr.openjdk.java.net/~roland/8212610/webrev.02/

Roland.