wined3d: Don't bother to unregister classes at process exit.

dlls/wined3d/wined3d_main.c

@@ -521,18 +521,15 @@ BOOL WINAPI DllMain(HINSTANCE hInstDLL, DWORD fdwReason, LPVOID lpv)
             return wined3d_dll_init(hInstDLL);
 
         case DLL_PROCESS_DETACH:
+            if (lpv) break;
             return wined3d_dll_destroy(hInstDLL);
 
         case DLL_THREAD_DETACH:
-        {
             if (!context_set_current(NULL))
             {
                 ERR("Failed to clear current context.\n");
             }
             return TRUE;
     }
-
-        default:
     return TRUE;
-    }
 }