Fix build problems on Windows 64-bit by casting.

src/circular-queue.cc

Index: src/circular-queue.cc
diff --git a/src/circular-queue.cc b/src/circular-queue.cc
index a7c25323e827842a41e00f4469ca917de72f6c0d..af650de5e79fcd17b21c94d208322274c9f578f0 100644
--- a/src/circular-queue.cc
+++ b/src/circular-queue.cc
@@ -58,8 +58,10 @@ SamplingCircularQueue::SamplingCircularQueue(int record_size_in_bytes,
   // updates of positions by different processor cores.
   const int positions_size =
       RoundUp(1, kProcessorCacheLineSize) +
-      RoundUp(sizeof(ProducerPosition), kProcessorCacheLineSize) +
-      RoundUp(sizeof(ConsumerPosition), kProcessorCacheLineSize);
+      RoundUp(static_cast<int>(sizeof(ProducerPosition)),
+              kProcessorCacheLineSize) +
+      RoundUp(static_cast<int>(sizeof(ConsumerPosition)),
+              kProcessorCacheLineSize);
   positions_ = NewArray<byte>(positions_size);
 
   producer_pos_ = reinterpret_cast<ProducerPosition*>(