better file open failure check (FSCORE-67)

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@6478 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_core.c

@@ -605,7 +605,8 @@ static void load_mime_types(void)
 	mime_path = switch_mprintf("%s/%s", SWITCH_GLOBAL_dirs.conf_dir, cf);
 	assert(mime_path);
 
-	if (!(fd = open(mime_path, O_RDONLY))) {
+	fd = open(mime_path, O_RDONLY);
+	if (fd <= 0) {
 		return;
 	}