remove qemu-kvm script in favor of symlink
    
    Since QEMU 4.0 upstream supported automatically favoring KVM if the
    executable ends with "kvm".  Unlike the script that is currently in
    use, this allows the user to specify an alternative accelerator with
    "-accel".
    
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>