InstrEmitter.h needs TargetMachine but relies on a forward declaration
of TargetMachine in MachineOperand.h. This patch adds a forward
declaration right in InstrEmitter.h.
While we are at it, this patch removes the one in MachineOperand.h,
where it is unnecessary.
class MCCFIInstruction;
class MDNode;
class ModuleSlotTracker;
-class TargetMachine;
class TargetIntrinsicInfo;
class TargetRegisterInfo;
class hash_code;
class SDDbgLabel;
class SDDbgValue;
class TargetLowering;
+class TargetMachine;
class LLVM_LIBRARY_VISIBILITY InstrEmitter {
MachineFunction *MF;