Native bindings to the SOFT_buffer_length_query extension.

This extension adds buffer queries to get the length in bytes, samples, and seconds.

Standard OpenAL only has queries for a buffer's storage size, the bits per sample, channel count, and sample rate, where the application needs to calculate what it wants from those. While this works alright for standard formats and most extension formats, it won't work for certain compressed formats like ADPCM. These extra queries ensure the application can get information about the buffer it may need.