Fix T99039: bpy.ops.sound.mixdown returns indecipherable error

Fix for {T99039}.

The problem was that `AUD_mixdown` and `AUD_mixdown_per_channel` were returning pointers to freed memory.

Two key changes are made:
1. The return value of those functions now simply return a bool as to whether the operation succeeded, instead of an optional error string pointer.
2. The error string buffer is now passed into the function to be filled in case an error occurs. In this way, the onus of memory ownership is unamibiguously on the caller.

Differential Revision: https://developer.blender.org/D15260

0 files changed, 0 insertions, 0 deletions