BUG/MEDIUM: config: fix missing initialization in numa_detect_topology()

The error path of the NUMA topology detection introduced in commit
b56a7c89a ("MEDIUM: cfgparse: detect numa and set affinity if needed")
lacks an initialization resulting in possible crashes at boot. No
backport is needed since that was introduced in 2.4-dev.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index f891697..5fdee40 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -2079,6 +2079,7 @@
 	ha_cpuset_zero(&node_cpu_set);
 
 	/* 1. count the sysfs node<X> directories */
+	node_dirlist = NULL;
 	node_dirlist_size = scandir(NUMA_DETECT_SYSTEM_SYSFS_PATH"/node", &node_dirlist, numa_filter, alphasort);
 	if (node_dirlist_size <= 1)
 		goto free_scandir_entries;