Try to fix Benjamin's r149781 on MSVC.

MSVC has complained the definition of "inline const DiagnosticBuilder &operator<<(const DiagnosticBuilder &DB, CanQualType T)" in clang/AST/CanonicalType.h.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149797 91177308-0d34-0410-b5e6-96231b3b80d8

Author: chapuni

include/clang/AST/CanonicalType.h

@@ -16,6 +16,7 @@
 #define LLVM_CLANG_AST_CANONICAL_TYPE_H
 
 #include "clang/AST/Type.h"
+#include "clang/Basic/Diagnostic.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/type_traits.h"
 #include <iterator>