Added SDL_copyp to avoid size mismatch when copying values (thanks @1bsyl!)

Closes https://github.com/libsdl-org/SDL/pull/5811

src/thread/windows/SDL_syscond_cv.c

@@ -261,7 +261,7 @@ SDL_CreateCond(void)
         }
 #endif
 
-        SDL_memcpy(&SDL_cond_impl_active, impl, sizeof(SDL_cond_impl_active));
+        SDL_copyp(&SDL_cond_impl_active, impl);
     }
     return SDL_cond_impl_active.Create();
 }