HPPA multiarching plan

[Joel Brobecker <brobecker@gnat.com>]

[This plan assumes that the ports to bsd/osf/pro are either obsoleted, or
taken care of by somebody else]

today I have tried to get a bigger picture of what to do to get the hppa
ports (partially) multi-arched. The targets that I will be converting
are:
	hppa*64*-*-hpux11*
	hppa*-*-hpux*
	hppa*-*-hiux*

I am assuming hiux is just a synonym of hpux?

The first thing I wasn't sure was to build an os_abi sniffer. So far,
given the short lists of targets, I suggest the following:

  - Add 2 new OSABI enums: HPPA_HPUX and HPPA64_HPUX.
    (it seems important to me to keep the OS name in the enum, to
    differentiate with HPPA_LINUX for instance)

  - The sniffer would then guess the correct value based like so:

    1. If object format is ELF
       -> OSABI = HPPA64_HPUX

    2. If object format is SOM
       -> OSABI = HPPA_HPUX
      
    Later on, when we want to add support for hppa-linux, the sniffer will
    need to be refined. I assume hppa-linux uses ELF? In which case we
    will probably have to dig into the ELF header to search for the clue
    that will reveal either hpux or linux.

What do you think?

-- 
Joel