Merge pull request #68 from eddyxu/debug_factorial

Use #ifdef to protect calling Factorial in benchmark_test.cc

test/benchmark_test.cc

diff --git a/test/benchmark_test.cc b/test/benchmark_test.cc
index e0f3262..108c3e9 100644
--- a/test/benchmark_test.cc
+++ b/test/benchmark_test.cc
@@ -171,7 +171,9 @@
 int main(int argc, const char* argv[]) {
   benchmark::Initialize(&argc, argv);
 
+#ifdef DEBUG
   assert(Factorial(8) == 40320);
+#endif
   assert(CalculatePi(1) == 0.0);
 
   TestReporter test_reporter;