Add flag to control whether self-recompilation information is written to interface

This patch adds the flag -fwrite-if-self-recomp which controls whether
interface files contain the information necessary to answer the
question:

  Do I need to recompile myself or is this current interface file
  suitable?

Why? Most packages are only built once either by a distribution or cabal
and then placed into an immutable store, after which we will never ask
this question. Therefore we can derive two benefits from omitting this
information.

* Primary motivation: It vastly reduces the surface area for creating
  non-deterministic interface files. See issue #10424 which motivated a
  proper fix to that issue. Distributions have long contained versions
  of GHC which just have broken self-recompilation checking (in order to
  get deterministic interface files).

* Secondary motivation: This reduces the size of interface files
  slightly.. the `mi_usages` field can be quite big but probably this
  isn't such a great benefit.

* Third motivation: Conceptually clarity about which parts of an
  interface file are used in order to **communicate** with subsequent
  packages about the **interface** for a module. And which parts are
  used to self-communicate during recompilation checking.

The main tracking issue is #22188 but fixes issues such as #10424 in a
proper way.