kernel: Add FIXME in copy_to_user()/copy_from_user()

kernel/src/memory/MemoryManager.cpp

@@ -428,6 +428,8 @@ namespace MemoryManager
         return true;
     }
 
+    // FIXME: Use memcpy() in both copy_to_user and copy_from_user().
+
     bool copy_to_user(void* user, const void* kernel, usize size)
     {
         uintptr_t user_ptr = (uintptr_t)user;