[RFA] Add support for 64-bit MIPS GNU/Linux targets

[Andrew Cagney]

> +  register_addr_data =
>> +    register_gdbarch_data (init_register_addr_data, 0);
>> +
>>    gdbarch_register_osabi (bfd_arch_mips, 0, GDB_OSABI_LINUX,
>>  			  mips_linux_init_abi);
>>    add_core_fns (&regset_core_fns);
> 
> 
> Blech.  So, the way _I_ would have done this would have been to put
> this in the tdep structure.  In fact I have several patches which add
> similar methods to the tdep structure, for signal handling.  Of course,
> this is not compatible with the way Andrew asked to leave the tdep
> struct in mips-tdep.c.  This is OK for now, but hopefully we can get
> rid of it eventually.  We could multi-arch register_addr (is that
> appropriate?  It's a native-only function, isn't it?) to do that.
> 

Using the gdbarch data mechanism is a good idea - it keeps that 
architecture dependency local to that file.  It definitly doesn't belong 
in the tdep structure since nothing, other than this file, needs it.

Hmm, should the actual code live in mips-linux-nat.c though?

enjoy,
Andrew