Improve random MAC generator
Improve random MAC generator

Use microseconds since the epoch instead of seconds.  When defining a guest
with multiple net devices specified (in which none of them have a MAC supplied),
it's possible for _net_rand_mac() to be called in rapid succession.

Also, initialize s - the seed value passed to rand_r().

Signed-off-by: Kaitlin Rupert <5d963ff58691ce861c80ea2b0deed9b0b88171bc@us.ibm.com>

libvirt/libvirt-cim,libvirt/libvirt-cim,libvirt/libvirt-cim