cpu: Introduce ENV_OFFSET macros

cpu: Introduce ENV_OFFSET macros

Introduce ENV_OFFSET macros which can be used in non-target-specific
code that needs to generate TCG instructions which reference CPUState
fields given the cpu_env register that TCG targets set up with a
pointer to the CPUArchState struct.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>