libev: make test work on linux too

Formula/libev.rb

@@ -56,7 +56,7 @@ class Libev < Formula
         return 0;
       }
     EOS
-    system ENV.cc, "-I#{include}", "-L#{lib}", "-lev", "-o", "test", "test.c"
+    system ENV.cc, "test.c", "-I#{include}", "-L#{lib}", "-lev", "-o", "test"
     input = "hello, world\n"
     assert_equal input, pipe_output("./test", input, 0)
   end