[RFC, RFA] multi-arch PREPARE_TO_PROCEED()

[Andrew Cagney]

David Smith wrote:

>                          hppa-tdep.c   linux-thread.c   lin-lwp.c   m3-nat.c
> Switch "inferior_pid"?      X                              X
> Flush cached frames?        X                              X
> Flush register data?        X                              X
> Update "stop_pc"?
> Select a new frame?
> 
> linux-thread.c just sets an internal variable (linuxthreads_step_pid) and
> then does some magic with that variable in linuxthreads_resume().  m3-nat.c
> calls a Mach3 specific switch_to_thread() function, which doesn't change
> inferior_pid at all (?).

Yes, ok.  Can of worms... Ulgh.  I'd check things in as they are.
Perhaphs just add a comment to each of the existing implementations
suggesting that they are potentially redundant.

	Andrew