transcode: destroy the mutex and condition only if they have been initialized.
transcode: destroy the mutex and condition only if they have been initialized.

If i_threads == 0, both are not initialized as the function transcode_video_new
returns before the call to vlc_mutex_init and vlc_cond_init.

This patch fixes a deadlock on vlc_cond_destroy called with an uninitialized
condition variable argument.

Signed-off-by: Thomas Guillem <5f50a84c1fa3bcff146405017f36aec1a10a9e38@gllm.fr>

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