cgroup: when comparing agent paths, use path_equal()

After all a path is a path is a path and we should use path_equal() to
comapre those.

src/basic/cgroup-util.c

@@ -899,7 +899,7 @@ int cg_install_release_agent(const char *controller, const char *agent) {
                 r = write_string_file(fs, agent, 0);
                 if (r < 0)
                         return r;
-        } else if (!streq(sc, agent))
+        } else if (!path_equal(sc, agent))
                 return -EEXIST;
 
         fs = mfree(fs);