Replace '#include ValueTypes.h' with forward declarations.

In some cases the include is pushed "downstream" (or removed if
unused).

llvm-svn: 203644
diff --git a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
index bbd4904..5d903e6 100644
--- a/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
+++ b/llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "X86ShuffleDecode.h"
+#include "llvm/CodeGen/ValueTypes.h"
 
 //===----------------------------------------------------------------------===//
 //  Vector Mask Decoding