Fix the missing IP aliases in the guest info.

Fix the missing IP aliases in the guest info.

IP aliases were missing in the guest info when libdnet is not used.

Previously tried to use the MAC address as the key to identify the IP aliases
on Linux.  However, that didn't work for vlan devices which share the same
MAC as the parent NIC.  The previous attempt was backed out.

Ideally, need to find a way to map the label name to the NIC name, but
have not been able to find a simple solution for this.  There might be a
netlink based solution but it is way too costly to do.

After more investigation, found out that a valid IP alias name must start
with the original NIC name followed by a colon.  Even though the ip addr allows
any string as the start of the NIC name, configuration file requires the colon.
In addition, ifconfig would error out when the name is not of the standard:
  ens192wwwww: error fetching interface information: Device not found

Therefore, a correctly configured system should use eth0:1, ens192:2 etc.

A lookup of libdnet source revealed the same assumption in the libdnet code.

/* Get addresses for this interface. */
for (ifr = intf->ifc.ifc_req; ifr < lifr && (ap + 1) < lap;
ifr = NEXTIFR(ifr)) {
/* XXX - Linux, Solaris ifaliases */
if ((p = strchr(ifr->ifr_name, ':')) != NULL)
*p = '\0';

Therefore, doing just the same.  Look for the colon, then trim it, and then
compare it with the NIC name.