Decoder segmentation fault in function edxt_fx()

This crash happens when decoding multi-channel input coded bitstream but it could happen in any given mdct-stereo core-coder frame.

To reproduce use the attached bitstream bs_48kbps_fb.192 as follows:

./IVAS_dec 5_1 48 bs_48kbps_fb.192 out.wav

Segmentation fault happens at frame 26 line 630 because the cosine pointer cosPtris not assigned. This happens because for the particular frame the length is 240 which is not included as a case in the assignment of tables to the cosine/sine pointers in lines 516-563 of the function.