Dropping arguments in inlining

Hi. I noticed an issue with the argument passing that has been introduced in https://github.com/inducer/loopy/pull/631 (I believe).

When we inline an inner kernel in a wrapper kernel, where the inner kernels takes many arguments but the code only depends on a subset of it, then in the C code, the inlined kernel only takes a subset of the arguments as parameters. A minimal example can be found here https://gist.github.com/sv2518/d6690f63b6827750fdaed9b01b4d9cea. I noticed that this only happens to `CTargets`, not for whatever Loo.py's default target is.

This is problematic in Firedrake for the vectorisation where we generate a loopy kernel first, do the inlining and vectorisation transformations and C codegen after that, and then pass the arguments dynamically. Meaning the arguments for the kernel before the transformations must be the same as after it. The MFE I linked above is coming from our test suite, the corresponding test is `tests/regression/test_par_loops.py::test_dict_order_parallel.`

Also sorry for the noise recently, it's mostly because I am still trying to get the Firedrake vectorisation PR landed.