Add reset()

include/rcp.h

@@ -118,6 +118,15 @@ public:
         other.ptr = nullptr;
     }
 
+    void reset()
+    {
+        if (ptr)
+        {
+            ptr->rcp_dec();
+            ptr = nullptr;
+        }
+    }
+
     T * get_raw() const
     {
         return ptr;