MSAN: use-of-uninitialized-value in lib_enc/lsf_enc.c:262:5 for EVS encoder

Basic info

Bug description

Clang MSAN sanitizer test in pipeline found an error:

==3479==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x56055c6c3551 in lsf_enc /builds/rep/ivas-codec-pc/ivas-codec/lib_enc/lsf_enc.c:262:5
    #1 0x56055c8a33a2 in acelp_core_enc /builds/rep/ivas-codec-pc/ivas-codec/lib_enc/acelp_core_enc.c:413:13
    #2 0x56055c4361d5 in evs_enc /builds/rep/ivas-codec-pc/ivas-codec/lib_enc/evs_enc.c:245:28
    #3 0x56055c3d18f4 in IVAS_ENC_EncodeFrameToSerial /builds/rep/ivas-codec-pc/ivas-codec/lib_enc/lib_enc.c:1348:28
    #4 0x56055c3b1b04 in main /builds/rep/ivas-codec-pc/ivas-codec/apps/encoder.c:882:28
    #5 0x7f14f466d1c9 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #6 0x7f14f466d28a in __libc_start_main csu/../csu/libc-start.c:360:3
    #7 0x56055c311614 in _start (/builds/rep/ivas-codec-pc/ivas-codec/CLANG1/IVAS_cod+0x38614) (BuildId: 019705be01e179f27e1eb6e7e073492a59686336)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /builds/rep/ivas-codec-pc/ivas-codec/lib_enc/lsf_enc.c:262:5 in lsf_enc
Exiting

Link to test pipeline: https://forge.3gpp.org/rep/ivas-codec-pc/ivas-codec/-/jobs/737864

Ways to reproduce

Activate origin-tracking (more detailed traceback about where the undefined value came from) by appending

 -fsanitize-memory-track-origins

in the Makefile at lines 71 and 72. Note that this may increase runtime heavily.

Using the scripts:

python3 scripts/IvasBuildAndRunChecks.py --checks CLANG1 -m MONO_mono_b05_13_dtx_nb_rs -p /path/to/my/local/ci_linux_ltv_local.json

or directly:

make clean
make -j CLANG=1
./IVAS_cod -dtx -max_band nb scripts/switchPaths/sw_nb5.bin 8 ltv48_MONO.wav bit