Add cl.h into filter_cl.c to make sure environment is set up right.
Add cl.h into filter_cl.c to make sure environment is set up right.

Also made a few small whitespace changes. As of right now, the OpenCL
filter_cl.c is completely unused, as the runtime-cpu-detect doesn't
actually cause any of the functions to be called.

awatry/libvpx.opencl,awatry/libvpx.opencl,awatry/libvpx.opencl,awatry/libvpx.opencl