include/qemu: Split out plugin-event.h

The usage in hw/core/cpu.h only requires QEMU_PLUGIN_EV_MAX.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230310195252.210956-7-richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20230315174331.2959-17-alex.bennee@linaro.org>
Reviewed-by: Emilio Cota <cota@braap.org>
3 files changed