systemd: fix to use ${libdir} for libraries

We need to use ${libdir} instead of ${exec_prefix}/lib for libraries.
Otherwise, we would meet do_install errors if multilib is enabled.

(From OE-Core rev: 6beeccb81416b0a7af6a4b19cb641f0d66a7198a)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/systemd/systemd_216.bb

@@ -129,7 +129,7 @@ do_install() {
 	fi
 
 	# Move libgudev back to ${rootlibdir} to keep backward compatibility
-	[ ${rootlibdir} != ${exec_prefix}/lib ] && mv -t ${D}${rootlibdir} ${D}${exec_prefix}/lib/libgudev*
+	[ ${rootlibdir} != ${libdir} ] && mv -t ${D}${rootlibdir} ${D}${libdir}/libgudev*
 
         # Delete journal README, as log can be symlinked inside volatile.
         rm -f ${D}/${localstatedir}/log/README
@@ -241,7 +241,7 @@ FILES_${PN} = " ${base_bindir}/* \
                 ${rootlibexecdir}/systemd/* \
                 ${systemd_unitdir}/* \
                 ${base_libdir}/security/*.so \
-                ${exec_prefix}/lib/libnss_* \
+                ${libdir}/libnss_* \
                 /cgroup \
                 ${bindir}/systemd* \
                 ${bindir}/busctl \