[RFA/testsuite] Tweak gdb.java/jmisc.java to pass on PowerPC

[Michael Elizabeth Chastain]

Okay, I'll volunteer, but I don't have any PPC hardware.  If you
send me a binary test program, will I be able to get somewhere with a
powerpc-unknown-eabi cross gdb?

I will see if I can at least make gdb throw up instead of going into a
silent death spiral.

Michael C