[ARM] Remove unused declaration RemapAddSubWithFlags

The corresponding function definition was removed by:

  commit e891654
  Author: Evan Cheng <evan.cheng@apple.com>
  Date:   Tue Aug 30 01:34:54 2011 +0000

While we are at it, this patch removes ARMPCLabelIndex, for which the
host compiler issues an unused variable warning.

llvm/lib/Target/ARM/ARMISelLowering.h

@@ -768,9 +768,6 @@ class VectorType;
 
     const InstrItineraryData *Itins;
 
-    /// ARMPCLabelIndex - Keep track of the number of ARM PC labels created.
-    unsigned ARMPCLabelIndex;
-
     // TODO: remove this, and have shouldInsertFencesForAtomic do the proper
     // check.
     bool InsertFencesForAtomic;
@@ -973,8 +970,6 @@ class VectorType;
 
     void EmitSjLjDispatchBlock(MachineInstr &MI, MachineBasicBlock *MBB) const;
 
-    bool RemapAddSubWithFlags(MachineInstr &MI, MachineBasicBlock *BB) const;
-
     MachineBasicBlock *EmitStructByval(MachineInstr &MI,
                                        MachineBasicBlock *MBB) const;