VarStreamArrayIterator needed non-const operator* overload

[amccarth]

Summary

Without this change, the operator-> provided by iterator_facade lost type qualifiers.

[inglorion]

iterator_facade_base is already supposed to provide operator-> when you supply operator*. Looking into this offline together, it seems the type checker is tripping over the const ValueType on line 160, and that providing a non-const operator* may fix that.

[amccarth]

Better solution after discussion with inglorion and zturner.

[inglorion]

lgtm!

llvm/include/llvm/Support/BinaryStreamArray.h

bool operator==(const IterType &R) const {
     return false;
   }
 
   const ValueType &operator*() const {
     assert(Array && !HasError);
     return ThisValue;
   }
 
+  const ValueType *operator->() const {
+    assert(Array && !HasError);
+    return &ThisValue;
+  }
+
   IterType &operator+=(unsigned N) {
     for (unsigned I = 0; I < N; ++I) {
       // We are done with the current record, discard it so that we are
       // positioned at the next record.
       IterRef = IterRef.drop_front(ThisLen);
       if (IterRef.getLength() == 0) {
         // There is nothing after the current record, we must make this an end
         // iterator.