feature: add devpts fd wrapper (#21)

This feature is intended to resolve devpts problem.

kernel/ksud.h

@@ -10,7 +10,7 @@ void on_post_fs_data(void);
 
 bool ksu_is_safe_mode(void);
 
-extern u32 ksu_devpts_sid;
+extern u32 ksu_file_sid;
 
 extern bool ksu_execveat_hook __read_mostly;
 extern int ksu_handle_pre_ksud(const char *filename);