Incorrect arch type does not clean up

[brendan-stephens]

If you neglect to change the qe.arch to the correct type (eg. x86), it will hang on the ssh auth and leave the qemu-system process in an uninterruptible state (does not respond to sighup).
Cleanup should look for and terminate residual processes on exit.

[ppggff]

Thanks, you are right, this may need a better stop or destroy implementation.