python/qemu: accel: Strengthen kvm_available() checks

    # Skip the first line which is the header.

    return [acc.strip() for acc in out.splitlines()[1:]]

def kvm_available(target_arch=None):

def kvm_available(target_arch=None, qemu_bin=None):

    """

    Check if KVM is available using the following heuristic:

      - Kernel module is present in the host;

      - Target and host arches don't mismatch;

      - KVM is enabled in the QEMU binary.

    @param target_arch (str): target architecture

    @param qemu_bin (str): path to the QEMU binary

    @return True if kvm is available, otherwise False.

    """

    if not os.access("/dev/kvm", os.R_OK | os.W_OK):

        return False

    if target_arch:

        host_arch = os.uname()[4]

    if target_arch and target_arch != host_arch:

        if target_arch != host_arch:

            if target_arch != ADDITIONAL_ARCHES.get(host_arch):

                return False

    return os.access("/dev/kvm", os.R_OK | os.W_OK)

    if qemu_bin and "kvm" not in list_accel(qemu_bin):

        return False

    return True