avformat: initialize probe data (fixes #11851)
avformat: initialize probe data (fixes #11851)

(cherry picked from commit 49bd1c657d960ba107d9db8752f716139a938eee)

jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2