clover: Implement clCreateProgramWithILKHR

clover: Implement clCreateProgramWithILKHR

v2: Use the same storage for OpenCL C sources and ILs representations
    (Karol Herbst, Francisco Jerez)
v3:
* Remove `program::has_source` and instead add a value to
  `program::il_type` for sources. (Francisco Jerez)
* Use `std::move()` on sources.
* Replace `CL_MAKE_VERSION(99999999u, 0u, 0u)` with
  `std::numeric_limits<uint32_t>::max()` (Francisco Jerez)

Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Pierre Moreau <dev@pmoreau.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/2078>