RFR(S) 8009721: Move the definition of class LRG_List

[Roland Westrelin]

> Problem: 
> The class PhaseLive in opto/live.hpp uses a data structure, class LRG_List, defined in opto/chaitin.hpp. Each time the class PhaseLive is used, chaitin.hpp needs to be included. This would make no sense if, for example, a new register allocator in C2 would like to use the class PhaseLive and because of this needs to include chaitin.hpp. 
> 
> Solution: 
> Move the definition of the class LRG_List from opto/chaitin.hpp to opto/live.hpp.

It looks good to me.

Roland.