libink: a message bus is not a peer

libink was written against the only bus it had, its own, where the
peer on the other end is the client.  A broker is not: it routes for
senders it names itself, expects a DESTINATION on anything addressed
through it, and answers on its own schedule rather than next.

Runlevels go on the wire as S and N rather than the digits Finit
keeps internally, since that is what a caller outside Finit means by
one.

The library stays a convenience library, linked into finit and
initctl and installed nowhere: the ABI promise waits until libink is
its own project.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/build.yml

@@ -62,16 +62,16 @@ jobs:
           tree /tmp || true
       - name: Check dependencies
         run: |
-          LD_LIBRARY_PATH=/tmp/lib ldd  /tmp/sbin/finit
+          ldd  /tmp/sbin/finit
           size /tmp/sbin/finit
-          LD_LIBRARY_PATH=/tmp/lib ldd  /tmp/sbin/initctl
+          ldd  /tmp/sbin/initctl
           size /tmp/sbin/initctl
-          LD_LIBRARY_PATH=/tmp/lib ldd  /tmp/sbin/reboot
+          ldd  /tmp/sbin/reboot
           size /tmp/sbin/reboot
       - name: Verify starting and showing usage text
         run: |
-          sudo env LD_LIBRARY_PATH=/tmp/lib /tmp/sbin/finit -h
-          sudo env LD_LIBRARY_PATH=/tmp/lib /tmp/sbin/initctl -h
+          sudo /tmp/sbin/finit -h
+          sudo /tmp/sbin/initctl -h
       - name: Enable unprivileged userns (unshare)
         run: |
           sudo sysctl kernel.apparmor_restrict_unprivileged_userns=0