Prevent redefinition of NOMINMAX

While this protection is not strictly necessary here, if someone
does a cut-and-paste into a header file it should be included.

testApp/misc/testSerialization.cpp

@@ -10,7 +10,7 @@
  *      Author: Miha Vitorovic
  */
 
-#ifdef _WIN32
+#if defined(_WIN32) && !defined(NOMINMAX)
 #define NOMINMAX
 #endif