[libFuzzer] initialize ValueBitMap::NumBits

llvm-svn: 282721
diff --git a/llvm/lib/Fuzzer/FuzzerValueBitMap.h b/llvm/lib/Fuzzer/FuzzerValueBitMap.h
index bc191e4..97f4c5e 100644
--- a/llvm/lib/Fuzzer/FuzzerValueBitMap.h
+++ b/llvm/lib/Fuzzer/FuzzerValueBitMap.h
@@ -69,7 +69,7 @@
   }
 
  private:
-  size_t NumBits;
+  size_t NumBits = 0;
   uintptr_t Map[kMapSizeInWords] __attribute__((aligned(512)));
 };