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.
Add a new function to find the global work size given the output image and
the required block alignment, then use it in the overlay, program and unsharp
filters. Fixes the overlay and unsharp filters applying the kernel to
locations outside the frame when subsampled planes are present.
