units: install user units as real files, not symlinks to ../system/

This was causing preset-all --global to create symlinks:

$ systemctl preset-all --global --root=/var/tmp/inst1
Created symlink /var/tmp/inst1/etc/systemd/user/shutdown.target → /usr/lib/systemd/user/../system/shutdown.target.
Created symlink /var/tmp/inst1/etc/systemd/user/sockets.target → /usr/lib/systemd/user/../system/sockets.target.
Created symlink /var/tmp/inst1/etc/systemd/user/timers.target → /usr/lib/systemd/user/../system/timers.target.
Created symlink /var/tmp/inst1/etc/systemd/user/paths.target → /usr/lib/systemd/user/../system/paths.target.
Created symlink /var/tmp/inst1/etc/systemd/user/bluetooth.target → /usr/lib/systemd/user/../system/bluetooth.target.
Created symlink /var/tmp/inst1/etc/systemd/user/printer.target → /usr/lib/systemd/user/../system/printer.target.
Created symlink /var/tmp/inst1/etc/systemd/user/sound.target → /usr/lib/systemd/user/../system/sound.target.
Created symlink /var/tmp/inst1/etc/systemd/user/smartcard.target → /usr/lib/systemd/user/../system/smartcard.target.
Created symlink /var/tmp/inst1/etc/systemd/user/busnames.target → /usr/lib/systemd/user/../system/busnames.target.

It is better to create units in a state that completely matches the presets, i.e.
preset-all should do nothing when invoked immediately after installation.

I'm sure it was confusing to users too, suggesting that system and user units
may somehow alias each other.

Makefile.am

@@ -575,7 +575,16 @@ dist_userunit_DATA = \
 	units/user/default.target \
 	units/user/exit.target \
 	units/user/graphical-session.target \
-	units/user/graphical-session-pre.target
+	units/user/graphical-session-pre.target \
+	units/user/bluetooth.target \
+	units/user/busnames.target \
+	units/user/paths.target \
+	units/user/printer.target \
+	units/user/shutdown.target \
+	units/user/smartcard.target \
+	units/user/sockets.target \
+	units/user/sound.target \
+	units/user/timers.target
 
 nodist_userunit_DATA = \
 	units/user/systemd-exit.service
@@ -6296,19 +6305,6 @@ SYSTEM_UNIT_ALIASES += \
 	reboot.target ctrl-alt-del.target \
 	getty@.service autovt@.service
 
-USER_UNIT_ALIASES += \
-	$(systemunitdir)/shutdown.target shutdown.target \
-	$(systemunitdir)/sockets.target sockets.target \
-	$(systemunitdir)/timers.target timers.target \
-	$(systemunitdir)/paths.target paths.target \
-	$(systemunitdir)/bluetooth.target bluetooth.target \
-	$(systemunitdir)/printer.target printer.target \
-	$(systemunitdir)/sound.target sound.target \
-	$(systemunitdir)/smartcard.target smartcard.target
-
-USER_UNIT_ALIASES += \
-	$(systemunitdir)/busnames.target busnames.target
-
 GENERAL_ALIASES += \
 	$(systemunitdir)/remote-fs.target $(pkgsysconfdir)/system/multi-user.target.wants/remote-fs.target \
 	$(systemunitdir)/getty@.service $(pkgsysconfdir)/system/getty.target.wants/getty@tty1.service \

units/user/bluetooth.target

@@ -0,0 +1 @@
+../bluetooth.target

units/user/busnames.target

@@ -0,0 +1 @@
+../busnames.target

units/user/paths.target

@@ -0,0 +1 @@
+../paths.target

units/user/printer.target

@@ -0,0 +1 @@
+../printer.target

units/user/shutdown.target

@@ -0,0 +1 @@
+../shutdown.target

units/user/smartcard.target

@@ -0,0 +1 @@
+../smartcard.target

units/user/sockets.target

@@ -0,0 +1 @@
+../sockets.target

units/user/sound.target

@@ -0,0 +1 @@
+../sound.target

units/user/timers.target

@@ -0,0 +1 @@
+../timers.target