GDB broken on MIPS targets with unmarked binaries

[Andrew Cagney]

> It delays the computation until it is needed.  It also happens to keep 
>> the old code working without having to add more macros :-)
> 
> 
> Doesn't work.  It's referenced in creating the register cache, which is
> still before we have an architecture.  We need to know this information
> earlier.  Any other ideas, or is my original patch OK?

I'll commit a work-around.

> By the way, I think the existing default: case in that switch is pretty
> pointless anyway.  Note that it selects an arbitrary number of argument
> registers.  It doesn't work when all the tools are configured mips-elf
> (default to O32), which is why I suggested some time ago that we just
> default to O32 in that configuration at least... that would make the
> test numbers suck a bit less, and reduce the black magic factor a bit.

Default for plain mips-elf?  Yes sounds like a good idea.  As the other 
variants get deleted they can fall back to that.

(I take it this is the default for mips-elf-{as,gcc}.

Andrew