Preserve the const qualifier returned from strstr().

--- a/src/parser.c
+++ b/src/parser.c
@@ -500,25 +500,26 @@ static void node_set_selinux(lsnode_t *node, const char * const ctx)
 
 static void node_set_name(lsnode_t *node, const char * const name)
 {
-	char *sub;
+	const char *sub;
+	const char *target;
 	char *tmp;
 	size_t len;
 
 	assert(name != NULL);
 
 	if ((node->mode & S_IFLNK) == S_IFLNK) {
 		#define LNK_DELIM " -> "
 		sub = strstr(name, LNK_DELIM);
 		if (sub) {
 			len = sub - name;
 			tmp = (char *)malloc(len + 1);
 			memcpy(tmp, name, len);
 			tmp[len] = '\0';
 			node->name = tmp;
-			tmp = sub + strlen(LNK_DELIM);
-			if (*tmp != '\0') {
-				node->data = strdup(tmp);
+			target = sub + strlen(LNK_DELIM);
+			if (*target != '\0') {
+				node->data = strdup(target);
 			}
 		} else {
 			node->name = strdup(name);
 		}