decoder: lock i_preroll_end
decoder: lock i_preroll_end

This variable will be acceded by other threads via future decoder queue
functions

Signed-off-by: Rémi Denis-Courmont <f0699137713be92736351a0674e79536595e4a60@remlab.net>

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc