Fix WinXP compatibility of kNet's Clock class.

Source/ThirdParty/kNet/src/Clock.cpp

@@ -15,6 +15,11 @@
 /** @file Clock.cpp
 	@brief */
 
+// Modified by Lasse Oorni for Urho3D
+
+// Urho3D: ensure that kNetBuildConfig.h is included for WinXP compatibility
+#include "kNetBuildConfig.h"
+
 #if defined(__unix__) || defined(__native_client__) || defined(EMSCRIPTEN) || defined(ANDROID) || defined(__APPLE__) || defined (__CYGWIN__)
 #include <time.h>
 #include <errno.h>