Also mark Type's dump() as 'used' to make it available in libclang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151037 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 29a07f3..412b51d 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -1706,7 +1706,7 @@
     return CanonicalType;
   }
   CanQualType getCanonicalTypeUnqualified() const; // in CanonicalType.h
-  void dump() const;
+  LLVM_ATTRIBUTE_USED void dump() const;
 
   static bool classof(const Type *) { return true; }