(#5) Don't crash the windows build just because PIPE is not implemented

examples/pipe.c

@@ -3,7 +3,11 @@
 
 int main(void)
 {
+#if _WIN32
+    WARN("Piping is not implemented on Windows yet");
+#else
     PIPE(IN("./nobuild.c"), CHAIN("cat"));
+#endif
 
     return 0;
 }