This stub should allow remote debugging of 32 bit and 64 bit targets. Single
stepping seems to work, as do breakpoints. If both breakpoints and single
stepping affect an instruction, gdb will stop at the instruction twice before
continuing. That's a little surprising, but is generally harmless.
We should always refer to the specific ISA in that arch directory.
This is especially necessary if we're ever going to make it to the
point where we actually have heterogeneous systems.
