package: Fix source path for systemd's service

Otherwise the link would appear broken in output/target it's not that
big a deal but at least it's coherent with what we already have.

Signed-off-by: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/chrony/chrony.mk

@@ -49,7 +49,7 @@ define CHRONY_INSTALL_INIT_SYSTEMD
 	$(INSTALL) -D -m 644 package/chrony/chrony.service \
 		$(TARGET_DIR)/usr/lib/systemd/system/chrony.service
 	mkdir -p $(TARGET_DIR)/etc/systemd/system/multi-user.target.wants
-	ln -sf /usr/lib/systemd/system/chrony.service \
+	ln -sf ../../../../usr/lib/systemd/system/chrony.service \
 		$(TARGET_DIR)/etc/systemd/system/multi-user.target.wants/chrony.service
 endef
 

package/dcron/dcron.mk

@@ -37,7 +37,7 @@ define DCRON_INSTALL_INIT_SYSTEMD
 	$(INSTALL) -D -m 644 package/dcron/dcron.service \
 		$(TARGET_DIR)/usr/lib/systemd/system/dcron.service
 	mkdir -p $(TARGET_DIR)/etc/systemd/system/multi-user.target.wants
-	ln -sf /usr/lib/systemd/system/dcron.service \
+	ln -sf ../../../../usr/lib/systemd/system/dcron.service \
 		$(TARGET_DIR)/etc/systemd/system/multi-user.target.wants/dcron.service
 endef
 

package/exim/exim.mk

@@ -137,7 +137,7 @@ define EXIM_INSTALL_INIT_SYSTEMD
 	$(INSTALL) -D -m 644 package/exim/exim.service \
 		$(TARGET_DIR)/usr/lib/systemd/system/exim.service
 	mkdir -p $(TARGET_DIR)/etc/systemd/system/multi-user.target.wants
-	ln -sf /usr/lib/systemd/system/exim.service \
+	ln -sf ../../../../usr/lib/systemd/system/exim.service \
 		$(TARGET_DIR)/etc/systemd/system/multi-user.target.wants/exim.service
 endef
 

package/inadyn/inadyn.mk

@@ -34,7 +34,7 @@ define INADYN_INSTALL_INIT_SYSTEMD
 	$(INSTALL) -D -m 644 package/inadyn/inadyn.service \
 		$(TARGET_DIR)/usr/lib/systemd/system/inadyn.service
 	mkdir -p $(TARGET_DIR)/etc/systemd/system/multi-user.target.wants
-	ln -sf /usr/lib/systemd/system/inadyn.service \
+	ln -sf ../../../../usr/lib/systemd/system/inadyn.service \
 		$(TARGET_DIR)/etc/systemd/system/multi-user.target.wants/inadyn.service
 endef