kvm tools: Embed init and init_stage2 into lkvm binary

kvm tools: Embed init and init_stage2 into lkvm binary

We generate guest init and init_stage2 on the fly and put them in

   ~/.lkvm/$guest/virt/init
   ~/.lkvm/$guest/virt/init_stage2
.

This makes 'lkvm run' no longer depending on guest/{int, init_stage2}.

Further, we can merge init and init_stage2 since there is no need to
split the init function into two stages any more.

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>