The core-coder duplicates several functions around non_linearity_fx() used for TD BWE. This issue is to track the harmonization of duplications in functions such as * non_linearity_fx() vs. non_linearity_ivas_fx() * non_linearity_scaled_copy() vs. non_linearity_scaled_copy_ivas() * cng_params_upd_fx() vs. cng_params_upd_ivas_fx() * calculate_hangover_attenuation_gain_fx() vs. calculate_hangover_attenuation_gain_ivas_fx() * cng_params_upd_fx() vs. cng_params_upd_ivas_fx() * CNG_enc_fx() vs. CNG_enc_ivas_fx() * shb_CNG_encod_fx() vs. shb_CNG_encod_ivas_fx() * swb_CNG_dec_fx() vs. swb_CNG_dec_ivas_fx() The harmonization is a pre-step for the harmonization of acelp_core_enc_fx(). <!--- Below are labels that will be added but are not shown in description. This is a template to help fill them. Add further information to the first row and remove and add labels as necessary.-->