units: synchronize Makefile and presets settings

Enable reboot.target and disable exit.target: the first is used on normal
machines, the second only in containers, and the more general one
should be enabled by default.

Also fix the Makefile to match what preset-all does.

With this and the previous commits, doing "make instal DESTDIR=…" followed
by "systemctl preset-all --root=…" doesn't result in any changes.

Makefile.am

@@ -634,6 +634,10 @@ EXTRA_DIST += \
 	units/rc-local.service.in \
 	units/halt-local.service.in
 
+GENERAL_ALIASES += \
+	$(systemunitdir)/reboot.target $(pkgsysconfdir)/system/ctrl-alt-del.target \
+	$(systemunitdir)/machines.target $(pkgsysconfdir)/system/multi-user.target.wants/machines.target
+
 # automake is broken and can't handle files with a dash in front
 # http://debbugs.gnu.org/cgi/bugreport.cgi?bug=14728#8
 units-install-hook:

system-preset/90-systemd.preset

@@ -24,8 +24,9 @@ disable debug-shell.service
 disable halt.target
 disable kexec.target
 disable poweroff.target
-disable reboot.target
+enable reboot.target
 disable rescue.target
+disable exit.target
 
 disable syslog.socket