vo: add params mutex

This mostly is added to resolve player command synchronization with VO
thread discussed in 477a0f83.

The current uses does not necessarily need this as they are all managed
by playloop. But for future use with other params that will be handy.

Those params are mostly to observe current state of VO and does not
necessarly need to be locked along with frame drawing, that changes the
params once at the end.

0 files changed, 0 insertions, 0 deletions