add missing mode to open() when using O_CREAT

--- kobs-ng-3.0.35-4.1.0/src/main.c
+++ kobs-ng-3.0.35-4.1.0/src/main.c
@@ -563,7 +563,7 @@
 	int sz = getpagesize();
 
 	from = open(file_name, O_RDONLY);
-	to = open(tmp_file, O_CREAT | O_RDWR);
+	to = open(tmp_file, O_CREAT | O_RDWR, 0644);
 	if (from < 0 || to < 0) {
 		fprintf(stderr, "unable to create a temporary file\n");
 		exit(5);