this could use a fair amount of polish its probably not going to get unless
you guys are interested in including it, then i would try and clean up
the magic numbers into set/show commands, e.g. using an itset
and other stuff.

anyhow i think it shows off 2 of the newer features of gdb

in my tests lockstep1 foo increments to 10 or so
and lockstep2 foo increments to 5 then back to 0.

execution continues until reaching 6, 4.
where it hands control back to the user with both inferiors stopped.

now if it only could debug i386 + x86_64 simultaneously i'd be set
probably a twisted version comming up :/