The events 'qemu_malloc' and 'qemu_free' used in the examples no longer exist,
so use 'qemu_vmalloc' and 'qemu_vfree' instead.
Signed-off-by: NLluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>