lavfi/opencl: Avoid deprecation warnings when built with post-1.2 headers

lavfi/opencl: Avoid deprecation warnings when built with post-1.2 headers

The intended target is OpenCL 1.2, so disable warnings for APIs deprecated
after that.  This primarily applies to clCreateCommandQueue(), we can't use
the replacement clCreateCommandQueueWithProperties() because it was
introduced in OpenCL 2.0.

Also remove some unnecessary includes from overlay and program filters so
that the define is available at the right moment.