Native bindings to the ALC_EXT_DEDICATED extension.

This extension provides two "routing" EFX effects that allow sounds to be sent to dedicated speaker channels. Audio rendered to the dedicated low frequency effect (EFFECT_DEDICATED_LOW_FREQUENCY_EFFECT) is routed to a subwoofer if one is present. Otherwise, it is discarded.

Audio rendered to the dedicated dialogue effect (EFFECT_DEDICATED_DIALOGUE) is routed to a front centre speaker if one is present. Otherwise, it is rendered to the front centre using the normal spatialisation logic.

Both effects support a gain control parameter DEDICATED_GAIN, which defaults to 1.