replace int(floor()) with int(), since that produces same results for non-negative values and is much faster on 32-bit x86

tests/resample_test.cpp

@@ -181,7 +181,7 @@ int main(int argc, char** argv)
 	int out_w, out_h, out_stride;
 
 	//resizer(argc, argv);
-    //performance(argc, argv);
+    performance(argc, argv);
 
 #if 1
 	test_suite(argc, argv);