AudioSourceInstance3dData::mFlags (possibly) uninitialized

[petrihakkinen]

AudioSourceInstance3dData::init() does not copy the value of mFlags from AudioSource, so the member is uninitialized until Soloud::update3dAudio() is called for the first time. This causes the value of LISTENER_RELATIVE flag to be random when Soloud::update3dVoices() is called from play3d() and thus the initial overall volume of the sound can be computed incorrectly. This in turn causes random voice drops if the incorrectly computed overall volume falls under the inaudible threshold (0.01).

Note that I have verified this only with my forked version of Soloud which has some customizations so I'm not entirely sure if the problem happens with latest version.