anv: added proper handling for input argument in intel_clc

anv: added proper handling for input argument in intel_clc

That was previously listed on the getopt_long struct but not actually
being used. This makes intel_clc argument processing easier as now
all of its arguments are handled with getopt and anything after the
special argument '--' is passed along to clang to form the final build
command.

Thanks to Dylan Baker for help with changes to the meson file.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19153>