OpenAL: Update to 1.20.1

[AniLeo]

Updates the OpenAL dependency from 1.19.1 to 1.20.1

OpenAL changelog for 1.20.0/1.20.1 is

Implemented the AL_SOFT_direct_channels_remix extension.
This extends AL_DIRECT_CHANNELS_SOFT to optionally remix input channels that don't have a matching output channel.
Implemented the AL_SOFT_bformat_ex extension.
This extends B-Format buffer support for N3D or SN3D scaling, or ACN channel ordering.
Fixed a potential voice leak when a source is started and stopped or restarted in quick succession.
Fixed a potential device reset failure with JACK.
Improved handling of unsupported channel configurations with WASAPI.
Such setups will now try to output at least a stereo mix.
Improved clarity a bit for the HRTF second-order ambisonic decoder.
Improved detection of compatible layouts for SOFA files in makemhr and sofa-info.
Added the ability to resample HRTFs on load.
MHR files no longer need to match the device sample rate to be usable.
Added an option to limit the HRTF's filter length.