Rename the rc binary to openrc

Debian requested this rename due to the "rc" binary conflicting with the
"rc" binary from the plan 9 shell.

We also add a deprecation warning to the binary when it is run as rc to
encourage users to switch to openrc instead.

X-Gentoo-Bug: 493958
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=493958

support/sysvinit/inittab

@@ -5,24 +5,24 @@
 id:3:initdefault:
 
 # System initialization, mount local filesystems, etc.
-si::sysinit:/sbin/rc sysinit
+si::sysinit:/sbin/openrc sysinit
 
 # Further system initialization, brings up the boot runlevel.
-rc::bootwait:/sbin/rc boot
+rc::bootwait:/sbin/openrc boot
 
-l0:0:wait:/sbin/rc shutdown
+l0:0:wait:/sbin/openrc shutdown
 l0s:0:wait:/sbin/halt -dhip
-l1:S1:wait:/sbin/rc single
-l2:2:wait:/sbin/rc nonetwork
-l3:3:wait:/sbin/rc default
-l4:4:wait:/sbin/rc default
-l5:5:wait:/sbin/rc default
-l6:6:wait:/sbin/rc reboot
+l1:S1:wait:/sbin/openrc single
+l2:2:wait:/sbin/openrc nonetwork
+l3:3:wait:/sbin/openrc default
+l4:4:wait:/sbin/openrc default
+l5:5:wait:/sbin/openrc default
+l6:6:wait:/sbin/openrc reboot
 l6r:6:wait:/sbin/reboot -d
 #z6:6:respawn:/sbin/sulogin
 
 # new-style single-user
-su0:S:wait:/sbin/rc single
+su0:S:wait:/sbin/openrc single
 su1:S:wait:/sbin/sulogin
 
 # TERMINALS