Use a single --library OpenCL for all targets.
Use a single --library OpenCL for all targets.

Previously, a separate syntax was used for the linked OpenCL library.
Now only one syntax is used for Linux/Windows/others. MacOS will still
need special treatment in the future to bring in the right framework.

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