assert in the encoder coming from a missing saturation

Basic info

• Fixed point:
  • Encoder (fixed): 20cb1008

Bug description

Assert cause by a missing saturation.

>	IVAS_cod.exe!L_add Line 1681	C
 	IVAS_cod.exe!gauss2v_ivas_fx Line 984	C
 	IVAS_cod.exe!gaus_encode_ivas_fx Line 181	C
 	IVAS_cod.exe!encod_unvoiced_ivas_fx Line 332	C
 	IVAS_cod.exe!acelp_core_enc_ivas_fx Line 1520	C
 	IVAS_cod.exe!ivas_core_enc_fx Line 358	C
 	IVAS_cod.exe!ivas_cpe_enc_fx Line 1285	C
 	IVAS_cod.exe!ivas_enc_fx Line 185	C

Ways to reproduce

ivas_cod -STEREO 2 32000 48 ltv48s.wav bit