Correct placement of calling convention keyword: must follow the return type.

Using __stdcall before the return type results in a warning with VC6 and an
error with VC9, place it after the return type.

Also use wxSTDCALL instead of just __stdcall for potentially better
compatibility with other compilers.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62800 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

samples/dll/my_dll.cpp

@@ -186,7 +186,7 @@ HANDLE gs_wxMainThread = NULL;
 
 
 //  wx application startup code -- runs from its own thread
-__stdcall unsigned MyAppLauncher(void* event)
+unsigned wxSTDCALL MyAppLauncher(void* event)
 {
     // Note: The thread that called run_wx_gui_from_dll() holds gs_wxStartupCS
     //       at this point and won't release it until we signal it.