Update opencl-headers to rev 11 via SR 809455
    
    https://build.opensuse.org/request/show/809455
    by user pluskalm + dimstar_suse
    - Update to version 2.2+git.20200512:
      * Add cl_half.h header (#60)
      * add tokens for cl_amd_device_attribute_query (#90)
      * Add Windows CI using Travis (#82)
      * update headers for OpenCL 3.0 (#88)
      * Add cl_khr_extended_versioning macro (#85)
      * Synchronize experimental enum etc with cl.xml (#83)
      * Include the DirectX sharing headers from CL/cl_icd.h. (#81)
      * add missing error code CL_CONTEXT_TERMINATED_KHR
      * Change license to Apache 2.0 (#76)
      * Add enum value for `cl_khronos_vendor_id` (#71)
      * Experimental enum cl_khronos_vendor_id (#75)
      * experimental enums for language queries
      * add experimental enum CL_COMMAND_SVM_MIGRATE_MEM
      * move two subgroup queries from cl_kernel_info to cl_kernel_sub_group_info