rt: Make rust_sched_launcher hide it's thread implementation

src/rt/rust_sched_launcher.cpp

@@ -10,8 +10,3 @@ rust_sched_launcher::rust_sched_launcher(rust_scheduler *sched,
       sched_loop(sched, srv, id),
       driver(&sched_loop) {
 }
-
-void
-rust_sched_launcher::run() {
-    driver.start_main_loop();
-}

src/rt/rust_sched_launcher.h

@@ -7,7 +7,7 @@
 
 class rust_sched_launcher
   : public kernel_owned<rust_sched_launcher>,
-    public rust_thread {
+    private rust_thread {
 public:
     rust_kernel *kernel;
 
@@ -18,7 +18,9 @@ private:
 public:
     rust_sched_launcher(rust_scheduler *sched, rust_srv *srv, int id);
 
-    virtual void run();
+    void start() { rust_thread::start(); }
+    void run() { driver.start_main_loop(); }
+    void join() { rust_thread::join(); }
     rust_sched_loop *get_loop() { return &sched_loop; }
 };
 

src/rt/sync/rust_thread.h

@@ -20,9 +20,7 @@ class rust_thread {
 
     void start();
 
-    virtual void run() {
-        return;
-    }
+    virtual void run() = 0;
 
     void join();
     void detach();