Skip . and .. in foreach_bridge test

If bridge is name 'bridge' then the test for ./bridge would succeed
and eventually cause a SEGV. Correct fix is to just skip . directories
in scan.
diff --git a/libbridge/libbridge_init.c b/libbridge/libbridge_init.c
index a7473bd..1c1acbd 100644
--- a/libbridge/libbridge_init.c
+++ b/libbridge/libbridge_init.c
@@ -49,7 +49,11 @@
 	char path[SYSFS_PATH_MAX];
 	struct stat st;
 
-	snprintf(path, SYSFS_PATH_MAX, SYSFS_CLASS_NET "%s/bridge", entry->d_name);
+	if (entry->d_name[0] == '.')
+		return 0;
+	
+	snprintf(path, SYSFS_PATH_MAX, 
+		 SYSFS_CLASS_NET "%s/bridge", entry->d_name);
 	return stat(path, &st) == 0 && S_ISDIR(st.st_mode);
 }