os2: thread: determine cancelable state with killable variable
os2: thread: determine cancelable state with killable variable

If thread cancel is disabled and cancel is requested, it causes a tight
infinite loop eating up CPU in cancellation points such as vlc_join(),
vlc_cond_wait() and vlc_cond_timedwait().

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

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