accel: Move HAX hThread to accelerator context

hThread variable is only used by the HAX accelerator,
so move it to the accelerator specific context.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230624174121.11508-9-philmd@linaro.org>
5 files changed