Group the map and methods used to query instruction ordering for trimVarLocs
(D82129) into a class. This will make it easier to reuse the functionality upcoming
patches.
Note:
In D86151 I add an InstructionOrdering member to DebugHandlerBase. I then call initialize on it in debugHandlerBase::beginFunction and it is passed to trimVarLocs and validThroughout.
why isn't this a constructor? does it get initialized multiple times?