By default, when using the -g switch, avr-gcc generates stabs debug
information. I think it would make more sense to test GDB against DWARF
information, because stabs is obsolete by now, and nobody work on it.
So change the simavr board to pass -gdwarf-4 as the debug flag.
The downside is that users are probably more likely to use just -g, so
we don't test GDB the same way as users are likely to use it. But in
this case, if somebody comes and asks for help with GDB for AVR, I
suggest we encourage them to use -gdwarf-4.
I can't give stats about how that changes test results, because the
testsuite is too broken. There is an internal error that happens quite
frequently that needs to be investigated: