[Bug] func_button OnDamaged output might have the wrong activator

[rtldg]

The issue is pretty apparent here since the OnDamaged output is fired with m_hActivator instead of info.GetAttacker(): https://github.com/ValveSoftware/source-sdk-2013/blob/238a15a79dd2c3c151e98eea8b39e5f161a93703/src/game/server/buttons.cpp#L301-L316 This means that the first time a button is damaged, it will not fire correctly, and subsequent damages can fire with the wrong activator.

Something like this might be the correct thing to do here:

-	m_OnDamaged.FireOutput(m_hActivator, this);
+	m_OnDamaged.FireOutput(info.GetAttacker(), this);