EMI: Guybrush is visible through the city hall door

[sev-]

When entering the city hall on Melee island, Guybrush can be seen through the door.

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I've just closed issue #1091 which was just a duplicate of this one. For reference, my steps to reproduce:

1b5d84a, OpenGL
start a new game
jump 120
goto town hall
enter door
Guybrush enters and closes the door. During the few seconds when Guybrush is talking with Elaine, he will become partly visible through the closed door.

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It is still there with version 0.4.0-git2cad855, confirmed on Linux with the 3 graphics engines.
The problem does not exist in the original version.

​https://github.com/residualvm/residualvm/issues/946