[ADT] Make the iterator adaptor utility a touch more general by

requiring full control over the various parameters to the std::iterator
concept / trait thing. This is a precursor for adjusting these things to
where you can write a bidirectional iterator wrapping a random access
iterator with custom increment and decrement logic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207487 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/User.h

@@ -131,8 +131,9 @@ public:
   /// Convenience iterator for directly iterating over the Values in the
   /// OperandList
   struct value_op_iterator
-      : iterator_adaptor_base<value_op_iterator, op_iterator, Value *, Value *,
-                              Value *> {
+      : iterator_adaptor_base<value_op_iterator, op_iterator,
+                              std::random_access_iterator_tag, Value *,
+                              ptrdiff_t, Value *, Value *> {
     explicit value_op_iterator(Use *U = nullptr) : iterator_adaptor_base(U) {}
 
     Value *operator*() const { return *I; }