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

llvm-svn: 152997
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
index 02dad45..9c6eefe 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
@@ -7,9 +7,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/MC/MCAsmBackend.h"
 #include "MCTargetDesc/PPCMCTargetDesc.h"
 #include "MCTargetDesc/PPCFixupKinds.h"
+#include "llvm/MC/MCAsmBackend.h"
 #include "llvm/MC/MCELFObjectWriter.h"
 #include "llvm/MC/MCMachObjectWriter.h"
 #include "llvm/MC/MCSectionMachO.h"