systemd: add hook to disable ldconfig.service

Since version 215, systemd installs a service to execute /sbin/ldconfig
when the sysinit target is reached.

Unfortunately, /sbin/ldconfig is not installed on a target built using a
glibc-based toolchain.

As this service is not mandatory, it is now disabled, thus avoiding a
warning in the journal.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/systemd/systemd.mk

@@ -149,10 +149,17 @@ define SYSTEMD_SANITIZE_PATH_IN_UNITS
 		-exec $(SED) 's,$(HOST_DIR),,g' {} \;
 endef
 
+# Disable ldconfig.service, as /sbin/ldconfig is not available when the
+# target is built with a glibc-based toolchain.
+define SYSTEMD_DISABLE_LDCONFIG_SERVICE_HOOK
+	rm -f $(TARGET_DIR)/lib/systemd/system/sysinit.target.wants/ldconfig.service
+endef
+
 SYSTEMD_POST_INSTALL_TARGET_HOOKS += \
 	SYSTEMD_INSTALL_INIT_HOOK \
 	SYSTEMD_INSTALL_MACHINEID_HOOK \
 	SYSTEMD_INSTALL_RESOLVCONF_HOOK \
+	SYSTEMD_DISABLE_LDCONFIG_SERVICE_HOOK \
 	SYSTEMD_SANITIZE_PATH_IN_UNITS
 
 define SYSTEMD_USERS