Add the necessary annotations (the mininum required, that is those
on return values. NULL parameters or container types may require
more), and the Autotools stuff to get a NetworkManager GIR for
libnm-util and a NMClient for libnm-glib.
rtnl_addr requires that all addresses have the "peer" attribute set in
order to be compared for equality, but this attribute is not normally
set. As a result, most addresses will not compare as equal even to
themselves, busting caching. We fix this for now by poking into the
guts of libnl if it is broken...
