Fix implicit narrowing warning in Parallelizer.h.

Eigen/src/Core/products/Parallelizer.h

diff --git a/Eigen/src/Core/products/Parallelizer.h b/Eigen/src/Core/products/Parallelizer.h
index 68ae78a..c3172aa 100644
--- a/Eigen/src/Core/products/Parallelizer.h
+++ b/Eigen/src/Core/products/Parallelizer.h
@@ -212,7 +212,7 @@
     // Note that the actual number of threads might be lower than the number of
     // requested ones
     Index actual_threads = omp_get_num_threads();
-    GemmParallelInfo<Index> info(i, actual_threads, task_info);
+    GemmParallelInfo<Index> info(i, int(actual_threads), task_info);
 
     Index blockCols = (cols / actual_threads) & ~Index(0x3);
     Index blockRows = (rows / actual_threads);
@@ -237,7 +237,7 @@
   auto task = [=, &func, &barrier, &task_info](int i)
   {
     Index actual_threads = threads;
-    GemmParallelInfo<Index> info(i, actual_threads, task_info);
+    GemmParallelInfo<Index> info(i, int(actual_threads), task_info);
     Index blockCols = (cols / actual_threads) & ~Index(0x3);
     Index blockRows = (rows / actual_threads);
     blockRows = (blockRows/Functor::Traits::mr)*Functor::Traits::mr;