ISM4 decoder detects BER

In the course of debugging !908 (merged), I encountered the following decoder output:

------ Running the decoder ------

Frames processed:       767
   Decoding error: BER detected in frame 766 !!!!!
771
   Decoding error: BER detected in frame 770 !!!!!
775
   Decoding error: BER detected in frame 774 !!!!!
1500

Command-line:

ivas_enc.exe -ism 4 scripts/testv/stvISM1.csv scripts/testv/stvISM2.csv scripts/testv/stvISM3.csv scripts/testv/stvISM4.csv 96000 48 scripts/testv/stv4ISM48s.wav bit
ivas_dec.exe scripts/testv/ls_setup_16ch_8+4+4.txt 48 bit syn.dec

At all three reported frames, the st->BER_detect flag is set to 1 for object 2 inside the HQ core, function hvq_dec(). @norvell, will you find time to look at it, please?