Fix for 3GPP issue 991: Crash in stereo_dft_dec_fx() for OMASA JBM rateswitch

[x] Added saturations for BASOPs which have arguments derived from FC CNG Buffers. These FD CNG buffers are saturated as the values of float at this point are greater than 64 which can't be fit as the Q-factor expected is 25. The origin of the saturated values starts with msCurrentMinSubWindow buffer calculated in minimum_statistics_fx() function. These values will further get used for other buffers of FD_CNG. As a result, these saturations would be needed at this place.
[x] might be related to #859.