[NFC] Declare the member data of class PostGenericScheduler as "protected" instead of "private"

[steven.zhang]

Summary

Some target might try to subclass the PostGenericScheduler to custom the scheduling strategy. We need to declare the member data of PostGenericScheduler as "protected", which acts the same as "GenericScheduler".

[fhahn]

LGTM, given we already do the same for GenericScheduler. Please wait a bit with committing, in case there are additional concerns.

[echristo]

I'd probably prefer something around giving targets an interface rather than this... but that's a lot more work :)

llvm/trunk/include/llvm/CodeGen/MachineScheduler.h

 };
 
 /// PostGenericScheduler - Interface to the scheduling algorithm used by
 /// ScheduleDAGMI.
 ///
 /// Callbacks from ScheduleDAGMI:
 ///   initPolicy -> initialize(DAG) -> registerRoots -> pickNode ...
 class PostGenericScheduler : public GenericSchedulerBase {
+protected:
   ScheduleDAGMI *DAG;
   SchedBoundary Top;
   SmallVector<SUnit*, 8> BotRoots;
 
 public:
   PostGenericScheduler(const MachineSchedContext *C):
     GenericSchedulerBase(C), Top(SchedBoundary::TopQID, "TopQ") {}