MFC: correct cross-references. This brings up the following deltas:

1.8 src/share/man/man4/ipsec.4
1.13 src/share/man/man4/ng_bpf.4
1.22 src/usr.sbin/lpr/lpr/printcap.5
1.9 src/lib/libc/sys/setresuid.2
1.108 src/share/man/man5/rc.conf.5
1.9 src/lib/libnetgraph/netgraph.3
1.6 src/libexec/pppoed/pppoed.8
1.28 src/share/man/man4/bpf.4
1.28 src/share/man/man4/netgraph.4
1.13 src/share/man/man4/tty.4
1.7 src/usr.sbin/nghook/nghook.8
1.264 src/usr.sbin/ppp/ppp.8