revamped gdb_mbuild.sh

[Andrew Cagney]

> PS: Something I forgot to mention.
>> 
>> The new script, once it has successfully configured, built, and run a 
>> target, replaces the BUILDDIR/TARGET directory with a BUILDDIR/TARGET 
>> file (-f removes this, this is how the script knows to not try to re-do 
>> a build).
>> 
>> Anyway, the significant thing here is that the file contains the output 
>> from the TARGET's ``(gdb) maint print architecture'' command.  Having 
>> that output for each architectures available [suddenly] makes it 
>> possible to examine/compare all the settings and, consequently, change 
>> those settings to something more logical.
>> 
>> enjoy,
>> Andrew
>> 
> 
> 
> What happens to the build logs?  Do we keep those?

At present both build and config logs, and the build directory get 
removed.  Only architecture output is left.

I think this is ok since, unlike before, the command is restartable.  If 
the build fails, just restart it with a more verbose option(1).

?
Andrew

(1) Although this doesn't help the mn10300's -j 2 build problem.  The 
second run mysteriously worked.