build: Don't leak generated files into distribution

gdbus-codegen will generate code that will need a too recent version of glib.
contrib/rpm: Fix Fedora 19 build
Merge remote-tracking branches 'lr/lr-unmanaged-slaves', 'lr/lr-ipv6-tokens', 'lr/lr-ap', 'lr/lr-rdisc-mtu' and 'lr/lr-rpm-build' into integration