In order to do this, stop using the cpu_in*/out* helpers, and instead
access address_space_io directly.
cpu_in* and cpu_out* remain for usage in the monitor, in qtest, and
in Xen.
Backports commit 3f7d84648607cc0fcb3812bb4b88978e2a7aa24f from qemu
helper_sysenter in qemu/target-i386/seg_helper.c didn't check properly if a call interrupt callback was registred.
It has been fixed by copying the helper_syscall behavior.
