[llvm][HashRecognize] Fix compiler warning on Arm 32-bit

/home/david.spickett/llvm-project/llvm/lib/Analysis/HashRecognize.cpp:100:54: warning:
comparison of integers of different signs:
'typename iterator_traits<ilist_iterator_w_bits<node_options<Instruction, true, false, void, true, BasicBlock>, false, false>>::difference_type' (aka 'int') and
'size_type' (aka 'unsigned int') [-Wsign-compare]
  100 |   return std::distance(Latch->begin(), Latch->end()) != Visited.size();
      |          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~

With a static cast to size_t.

I thought about using Latch->size() but this skips a call to `It.setHeadBit(true);`
and I'm not sure whether that would make a difference in this context.

Author: DavidSpickett

llvm/lib/Analysis/HashRecognize.cpp

@@ -97,7 +97,8 @@ static bool containsUnreachable(const Loop &L,
       }
     }
   }
-  return std::distance(Latch->begin(), Latch->end()) != Visited.size();
+  return static_cast<size_t>(std::distance(Latch->begin(), Latch->end())) !=
+         Visited.size();
 }
 
 /// A structure that can hold either a Simple Recurrence or a Conditional