gnetworkmonitornetlink: filter out IPv6 LL MC changes
gnetworkmonitornetlink: filter out IPv6 LL MC changes

For some reason, IPv6 link-local multicast routing changes all the
time. GNetworkMonitorBase was already ignoring them for purposes of
emitting network-changed, but GNetworkMonitorNetlink would still
trigger a re-dump after getting one, so network-changed would end up
getting emitted anyway.

tchakabam/glib,MathieuDuponchelle/glib,johne53/MB3Glib,tamaskenez/glib,MathieuDuponchelle/glib,cention-sany/glib,tchakabam/glib,tamaskenez/glib,johne53/MB3Glib,lukasz-skalski/glib,mzabaluev/glib,cention-sany/glib,ieei/glib,krichter722/glib,MathieuDuponchelle/glib,endlessm/glib,ieei/glib,johne53/MB3Glib,Distrotech/glib,mzabaluev/glib,Distrotech/glib,gale320/glib,krichter722/glib,cention-sany/glib,tamaskenez/glib,Distrotech/glib,cention-sany/glib,mzabaluev/glib,johne53/MB3Glib,cention-sany/glib,gale320/glib,krichter722/glib,krichter722/glib,gale320/glib,ieei/glib,johne53/MB3Glib,johne53/MB3Glib,gale320/glib,endlessm/glib,Distrotech/glib,gale320/glib,ieei/glib,ieei/glib,lukasz-skalski/glib,lukasz-skalski/glib,tchakabam/glib,mzabaluev/glib,lukasz-skalski/glib,MathieuDuponchelle/glib,mzabaluev/glib,endlessm/glib,endlessm/glib,lukasz-skalski/glib,tchakabam/glib,krichter722/glib,MathieuDuponchelle/glib,tamaskenez/glib,Distrotech/glib,tamaskenez/glib,endlessm/glib,tchakabam/glib