Fix MSVC signed/unsigned comparison warning

llvm-svn: 316161
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index a15a12d..7b1d644 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -316,7 +316,7 @@
   // to them without checking for overflows, and we already don't want to
   // analyze *massive* trip counts, so we force the max to be reasonably small.
   assert(UnrollMaxIterationsCountToAnalyze <
-             (std::numeric_limits<int>::max() / 2) &&
+             (unsigned)(std::numeric_limits<int>::max() / 2) &&
          "The unroll iterations max is too large!");
 
   // Only analyze inner loops. We can't properly estimate cost of nested loops