"g_assert_cmpint (x, ==, y)" is nicer than "g_assert (x == y)",
because if it fails, it shows you the values of x and y in the assert
message. Likewise g_assert_cmpstr().
The "ifindex > 0" checks still just use g_assert(), since we don't
need to distinguish specific negative values there.
In some cases, callers don't need to distinguish, eg,
ip4-address-added from ip6-address-added, but just need to know what
device the event occurred on. Make this simpler by including the
ifindex as a separate explicit argument, allowing callers to just
ignore the struct part.
Extend nm-platform to support IPv4 and IPv6 address management.
Address features:
* Retrieve the list of IPv4 and IPv6 addresses
* Add/delete/lookup IPv4 and IPv6 addresses
* Flush all non-linklocal addresses
