[rfa/testsuite] Get the inferior to dump core

[Andrew Cagney]

> I'm not too worried about the interface (!), it's standardizing
> the guts that I'm worried about.

I was thinking that bigcore.exp's could be moved to gdb.exp where they 
can be used by other corefile tests with that bug - worry about fancying 
the guts if/when there's a need.

Andrew

>   - portable way to set the core dump size to "unlimited".
>     i suspect this is more portable to do at the C level with
>     setrlimit() rather than the shell level with the bitter
>     comments about braindamaged shells and ulimit.
> 
>   - creating a subdirectory
>     corefile.exp does this at the TCL level, which immediately
>     runs into a build != host problem.  Again I suspect this
>     might be better to do in the inferior program:
>       mkdir("coredir");
>       chdir("coredir");
>     coredir does not have to be unique.
> 
>   - picking up the core file
>     there should be exactly ONE file in coredir.  If there are
>     zero files, or two more files, then the test script cannot
>     proceed.
> 
>     The problem is figuring out the name of that file.
>     It's on the host machine so just "glob" will not cut it.
>     I don't know if there's a "remote glob" available or what.
> 
>     After figuring out the name of the file, do remote_upload
>     to get it back to the build machine to a fixed name.
> 
> That's just a half-assed look at gcore.exp.
> 
> Now, is it worth anyone's time to actually do this? 
> 
> I don't want to get into it myself because I want to get into
> "user specifies which compiler to run for each language".
> That's high priority and it's a big overhaul.