ccid: make threads joinable

Destroying a mutex that another thread might have just unlocked
is racy.  It usually works, but you cannot do that in general and
can lead to deadlocks or segfaults.  Change ccid to use joinable
threads instead.

(Also, qemu_mutex_init/qemu_cond_init were missing).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
