Fix ComputeAngleGains
Fix ComputeAngleGains

The old code would improperly handle speakers just inside or outside the
coverage area if it had to be inverted. It also didn't properly handle when
only one speaker was outside of the covered area.

franklixuefei/openal-soft,mmozeiko/OpenAL-Soft,Wemersive/openal-soft,BeamNG/openal-soft,irungentoo/openal-soft-tox,franklixuefei/openal-soft,EddieRingle/openal-soft,alexxvk/openal-soft,Wemersive/openal-soft,arkana-fts/openal-soft,dapetcu21/openal-soft,arkana-fts/openal-soft,alexxvk/openal-soft,aaronmjacobs/openal-soft,irungentoo/openal-soft-tox,rryan/openal-soft,aaronmjacobs/openal-soft,EddieRingle/openal-soft,jims/openal-soft,rryan/openal-soft,BeamNG/openal-soft,mmozeiko/OpenAL-Soft,jims/openal-soft