clover: Avoid warnings from new OpenCL headers

* Avoid warnings from references to deprecated CL 1.0, 1.2, 2.0 and 2.1 APIs.
* Avoid warnings from not defining CL_TARGET_OPENCL_VERSION.

Reviewed-by: Karol Herbst <kherbst@redhat.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
4 files changed