make sure update_late isn't executed when dt=0

simgear/sound/sample_openal.cxx

@@ -183,4 +183,7 @@ void SGSoundSample::update_absolute_position() {
 
      orient = SGQuatd::fromRealImag(0, _relative_pos) * _orientation;
     _absolute_pos = -SGVec3d::fromGeod(_base_pos) -orient.rotate(SGVec3d::e1());
+
+    float vel = length(_velocity);
+    _velocity = toVec3d(_orivec * vel);
 }

simgear/sound/soundmgr_openal.cxx

@@ -222,7 +222,7 @@ void SGSoundMgr::unbind ()
 
 // run the audio scheduler
 void SGSoundMgr::update_late( double dt ) {
-    if (_working) {
+    if (_working && dt != 0.0) {
         alcSuspendContext(_context);
 
         sample_group_map_iterator sample_grp_current = _sample_groups.begin();