accel/hvf: Report missing com.apple.security.hypervisor entitlement

accel/hvf: Report missing com.apple.security.hypervisor entitlement

We need the QEMU binary signed to be able to use HVF.
Improve the following:

  $ ./qemu-system-aarch64-unsigned -M virt -accel hvf
  qemu-system-aarch64-unsigned: -accel hvf: Error: ret = HV_DENIED (0xfae94007, at ../../accel/hvf/hvf-accel-ops.c:339)
  Abort trap: 6

to:

  $ ./qemu-system-aarch64-unsigned -M virt -accel hvf
  qemu-system-aarch64-unsigned: -accel hvf: Could not access HVF. Is the executable signed with com.apple.security.hypervisor entitlement?

Suggested-by: Shatyuka <shatyuka@qq.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2800
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Mads Ynddal <mads@ynddal.dk>
Message-Id: <20250702185332.43650-29-philmd@linaro.org>