[non-BE] Resolve "IGF is not applied correctly in frames concealed by tonal MDCT concealment"
Reason why this change is needed
This is a floating point follow up to sa4/audio/ivas-basop#905 (closed)
Description of the change
For the first concealed frame, the igf spectrum above the cross over frequency is set to zero as in the following frames. It will later be reconstructed using the sign flipt lower part instead of using the igf spectrum form the last valid frame which may contain zero energy spectral lines which may disturb the IGF processing.
Affected operating points
Tonal MDCT concealment
Related to #1212
Edited by Markus Werner