Integrated David Ludwig's support for Windows RT

src/loadso/windows/SDL_sysloadso.c

@@ -33,7 +33,15 @@ void *
 SDL_LoadObject(const char *sofile)
 {
     LPTSTR tstr = WIN_UTF8ToString(sofile);
+#ifdef __WINRT__
+    /* WinRT only publically supports LoadPackagedLibrary() for loading .dll
+       files.  LoadLibrary() is a private API, and not available for apps
+       (that can be published to MS' Windows Store.)
+    */
+    void *handle = (void *) LoadPackagedLibrary(tstr, 0);
+#else
     void *handle = (void *) LoadLibrary(tstr);
+#endif
     SDL_free(tstr);
 
     /* Generate an error message if all loads failed */