MINOR: sock: add interface and namespace length to xfer_sock_list

This will ease and speed up comparisons in FD lookups.
diff --git a/include/haproxy/sock-t.h b/include/haproxy/sock-t.h
index 999c16f..ee803ab 100644
--- a/include/haproxy/sock-t.h
+++ b/include/haproxy/sock-t.h
@@ -33,6 +33,8 @@
 	int options; /* socket options as LI_O_* */
 	char *iface;
 	char *namespace;
+	int if_namelen;
+	int ns_namelen;
 	struct xfer_sock_list *prev;
 	struct xfer_sock_list *next;
 	struct sockaddr_storage addr;
diff --git a/src/haproxy.c b/src/haproxy.c
index 8381269..7eb5c0e 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1275,6 +1275,7 @@
 			}
 			memcpy(xfer_sock->namespace, &tmpbuf[curoff], len);
 			xfer_sock->namespace[len] = 0;
+			xfer_sock->ns_namelen = len;
 			curoff += len;
 		}
 		if (curoff >= maxoff) {
@@ -1295,6 +1296,7 @@
 			}
 			memcpy(xfer_sock->iface, &tmpbuf[curoff], len);
 			xfer_sock->iface[len] = 0;
+			xfer_sock->if_namelen = len;
 			curoff += len;
 		}
 		if (curoff + sizeof(int) > maxoff) {