Resolve "USAN: SEGV in lib_com/tools_fx.c:3670:16"

• Related issues: #2376 (closed)
• Requested reviewers:

Reason why this change is needed

• USAN: SEGV in lib_com/tools_fx.c:3670:16

Description of the change

• Fix USAN error introduced by FIX_2344_ALIGN_PREPROC. Fixes OOB access during MDCT -> TD stereo switching.

Affected operating points

• All is BE on the short self-test. Fixes segfault on the long self-test.

Closes #2376 (closed)