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/Hexagon/HexagonTargetMachine.h b/lib/Target/Hexagon/HexagonTargetMachine.h
index 30fe9a6..0336965 100644
--- a/lib/Target/Hexagon/HexagonTargetMachine.h
+++ b/lib/Target/Hexagon/HexagonTargetMachine.h
@@ -14,13 +14,13 @@
 #ifndef HexagonTARGETMACHINE_H
 #define HexagonTARGETMACHINE_H
 
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetData.h"
 #include "HexagonInstrInfo.h"
 #include "HexagonSubtarget.h"
 #include "HexagonISelLowering.h"
 #include "HexagonSelectionDAGInfo.h"
 #include "HexagonFrameLowering.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetData.h"
 
 namespace llvm {