Update ALC_OUTPUT_LIMITER_SOFT to handle ALC_DONT_CARE_SOFT
Update ALC_OUTPUT_LIMITER_SOFT to handle ALC_DONT_CARE_SOFT

Essentially just adding a comment about it. Since we default to on, the
behavior already fit.

aaronmjacobs/openal-soft,aaronmjacobs/openal-soft