[libFuzzer] fix 32-bit build

llvm-svn: 249646
diff --git a/llvm/lib/Fuzzer/FuzzerMutate.cpp b/llvm/lib/Fuzzer/FuzzerMutate.cpp
index 0e8429b..74ae0cb 100644
--- a/llvm/lib/Fuzzer/FuzzerMutate.cpp
+++ b/llvm/lib/Fuzzer/FuzzerMutate.cpp
@@ -61,7 +61,7 @@
 size_t MutationDispatcher::Mutate_ShuffleBytes(uint8_t *Data, size_t Size,
                                                size_t MaxSize) {
   assert(Size);
-  size_t ShuffleAmount = Rand(std::min(Size, 8UL)) + 1;  // [1,8] and <= Size.
+  size_t ShuffleAmount = Rand(std::min(Size, (size_t)8)) + 1;  // [1,8] and <= Size.
   size_t ShuffleStart = Rand(Size - ShuffleAmount);
   assert(ShuffleStart + ShuffleAmount <= Size);
   std::random_shuffle(Data + ShuffleStart, Data + ShuffleStart + ShuffleAmount,