Update RNBRemote to handle the new pseudo_regs field added to DNBRegisterInfo
back in r173096 by Greg.  When constructing a g packet or parsing a G packet,
and we're iterate over our register list, skip registers that are actually
just slices of other, real, registers.  For instance, eax is 32-bits of rax
on x86_64.
<rdar://problem/15104187>