fixed compiler warning

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402350

examples/bayes_net_gui_ex.cpp

@@ -159,6 +159,7 @@ int main()
 int WINAPI WinMain (HINSTANCE, HINSTANCE, PSTR cmds, int)
 {
     main();
+    return 0;
 }
 #endif
 

examples/gui_api_ex.cpp

@@ -213,6 +213,7 @@ int WINAPI WinMain (
 )
 {
     main();
+    return 0;
 }
 #endif