kvm tools: Call executable 'lkvm' and add 'vm' alias

kvm tools: Call executable 'lkvm' and add 'vm' alias

Several people have raised up the issue with our 'kvm' executable name. Rusty
came up with 'lkvm' which even Ingo is reasonably happy with:

  I could live with:

   - keeping 'tools/kvm/' as the tool project name

   - 'lkvm' as the binary

   - a command alias binary (hardlink) to 'vm'. I just checked,
     it's not used by any other package.

  ... and be done with it?

  'lkvm' rhymes nicely to 'lkml' as well, so it's not a 100% bad
  name.

Suggested-by: Rusty Russell <rusty@rustcorp.com.au>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Pekka Enberg <penberg@kernel.org>