Mario drop held object

mario_drop_held_object is a titular function within Super Mario 64's code. It only does anything if Mario is holding an object.

The function goes as follows:

1. If holding a water shell, stop_shell_music()
2. The object's held state becomes bhvCarrySomething4 which I assume means "dropped"
3. The object's position is at the HOLP but at Mario's y position
4. The object's moveAngleYaw becomes Mario's facing angle
5. Mario's heldObj is NULL