Use-of-uninitialized-value error in SBA DTX modes

Basic info

• Commit SHA: f5e913a8
• Platform: Linux

Bug description

In recent sanitizer test jobs, Clang msan reports:

==145287==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x50138c in dtx /local/knj/ivas-codec/lib_enc/dtx.c:258:168
    #1 0xa8e08b in front_vad_spar /local/knj/ivas-codec/lib_enc/ivas_front_vad.c:434:9
    #2 0x68a462 in ivas_spar_enc /local/knj/ivas-codec/lib_enc/ivas_spar_encoder.c:296:20
    #3 0x569f1c in ivas_enc /local/knj/ivas-codec/lib_enc/ivas_enc.c:258:28
    #4 0x4b7d7e in IVAS_ENC_EncodeFrameToSerial /local/knj/ivas-codec/lib_enc/lib_enc.c:1134:24
    #5 0x49e6c2 in main /local/knj/ivas-codec/apps/encoder.c:747:24
    #6 0x7f8deb003d09 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x23d09)
    #7 0x41f579 in _start (/local/knj/ivas-codec/CLANG1/IVAS_cod+0x41f579)

SUMMARY: MemorySanitizer: use-of-uninitialized-value /local/knj/ivas-codec/lib_enc/dtx.c:258:168 in dtx
Exiting

Happens also for non-planar SBA.

Ways to reproduce

Example for 32kbps FB, see pipeline log for other modes

git checkout f5e913a
make clean
make -j CLANG=1
./IVAS_cod -sba -3 -dtx -max_band fb 32000 16 ltv48_HOA3.wav bit