winrt: Removed WinRT/Windows Phone/UWP support.

Fixes #10724.

src/loadso/windows/SDL_sysloadso.c

@@ -29,23 +29,13 @@
 
 void *SDL_LoadObject(const char *sofile)
 {
-    void *handle;
-    LPWSTR wstr;
-
     if (!sofile) {
         SDL_InvalidParamError("sofile");
         return NULL;
     }
-    wstr = WIN_UTF8ToStringW(sofile);
-#ifdef SDL_PLATFORM_WINRT
-    /* WinRT only publicly supports LoadPackagedLibrary() for loading .dll
-       files.  LoadLibrary() is a private API, and not available for apps
-       (that can be published to MS' Windows Store.)
-    */
-    handle = (void *)LoadPackagedLibrary(wstr, 0);
-#else
-    handle = (void *)LoadLibrary(wstr);
-#endif
+
+    LPWSTR wstr = WIN_UTF8ToStringW(sofile);
+    void *handle = (void *)LoadLibrary(wstr);
     SDL_free(wstr);
 
     // Generate an error message if all loads failed