x86: use caller supplied CPUState for interrupt related stuff

Several x86 specific functions are called from cpu-exec.c with the
assumption that global env register is valid. This will be changed
later, so make the functions use caller supplied CPUState parameter.

It would be cleaner to move the functions to helper.c, but there are
quite a lot of dependencies between do_interrupt() and other functions.

Add helpers for svm_check_intercept() and cpu_cc_compute_all() instead
of calling the helper (which uses global env, AREG0) directly.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
