Follow-up to c9fe9afa, proper fix for HOOK_BASFFS_UP mess

Instead of the revert in c9fe9afa, we restore HOOK_BASFFS_UP to its
proper place at the end of fs_mount_all().  For this to not cause any
regressions we add a new hook, HOOK_SVC_PLUGIN, and update all plugins
that call service_register() to run at the new hook.

This will cause regressions for external 3rd party plugins that rely on
HOOK_BASEFS_UP to be called at its previous postion.  Nevertheless, this
is the proper fix to the problem.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/conf.c

@@ -1209,6 +1209,9 @@ int conf_init(uev_ctx_t *ctx)
 	/* Initialize global rlimits, e.g. for built-in services */
 	memcpy(global_rlimit, initial_rlimit, sizeof(global_rlimit));
 
+	dbg("Allow plugins to register early runlevel 1 run/task/services ...");
+	plugin_run_hooks(HOOK_SVC_PLUGIN);
+
 	/* Read global rlimits and global cgroup setup from /etc/finit.conf */
 	parse_conf(finit_conf, 0);