use-of-uninitialized-value in mcc read header

use-of-uninitialized-value in mcc read header: a task in MiMo-V2.6-RL-harbor-cyber: MiMo-V2.6-RL Cyber (Harbor) (Harbor dataset). MemorySanitizer: use-of-uninitialized-value in function mcc read header in file ffmpeg/libavformat/mccdec.c