Function check_min_vararg_count

pub fn check_min_vararg_count<'a, 'tcx, const N: usize>(
    name: &'a str,
    args: &'a [OpTy<'tcx>],
) -> InterpResult<'tcx, &'a [OpTy<'tcx>; N]>

Check that the number of varargs is at least the minimum what we expect. Fixed args should not be included.