PREPARE_TO_PROCEED; Was: More multi-arch and cleanups for m68k-linux

[Andrew Cagney]

> The only thing that prevents m68k-linux from advancing to multi-arch
> level 2 is the PREPARE_TO_PROCEED definition in config/nm-linux.h.
> How can this be multi-arched given that this is a native-only thing?

I _think_ the current plan is along the lines of make 
generic_prepare_proceed(?) the default, and leave HP/UX as the exception.

Does the generic version work on GNU/Linux?  (Hmm??? nothing appears to 
currently use it!)

Andrew