Update ARM machine configuration

Signed-off-by: Luca Bruno <lucab@debian.org>
HostFiles: rework sub-opcode extraction

Signed-off-by: Luca Bruno <lucab@debian.org>
Make use of S2E_TARGET_CONC_LIMIT and CPU_CONC_LIMIT

Minimize target-specific code and number of #ifdef, by reusing the
S2E_TARGET_CONC_LIMIT and CPU_CONC_LIMIT macro when handling CPU state
offsets and areas, in conjuction with the neutral CPUArchState struct.

Signed-off-by: Luca Bruno <lucab@debian.org>