DEBUG initialisation missing for fixed point
# Basic info
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* Encoder (fix) : e1432023
# Bug description
An initialisation is missing in debug, making it impossible to force the stereo mode to FD or TD
```
#ifdef DEBUGGING
( *phIvasEnc )->cmd_stereo = false;
#endif
```
should be added to IVAS_ENC_Open_fx() (currently that has been added to IVAS_ENC_Open() which is not used during fixed point encoder initialisation.
@malenovsky, I'm not sure if there is already a MR where it could be added.
# Ways to reproduce
(Clear steps or refer to a failing automated test, e.g. with a pipeline link)
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issue