Reorder includes in Target backends to following coding standards. Remove some superfluous forward declarations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152997 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPC.h b/lib/Target/PowerPC/PPC.h
index 5dc1863..24a7178 100644
--- a/lib/Target/PowerPC/PPC.h
+++ b/lib/Target/PowerPC/PPC.h
@@ -25,14 +25,11 @@
 namespace llvm {
   class PPCTargetMachine;
   class FunctionPass;
-  class formatted_raw_ostream;
   class JITCodeEmitter;
-  class Target;
   class MachineInstr;
   class AsmPrinter;
   class MCInst;
-  class TargetMachine;
-  
+
   FunctionPass *createPPCBranchSelectionPass();
   FunctionPass *createPPCISelDag(PPCTargetMachine &TM);
   FunctionPass *createPPCJITCodeEmitterPass(PPCTargetMachine &TM,