put prototype for thread_yield() in core/include

core/include/thread.h

@@ -66,6 +66,11 @@ const char *thread_getname(int pid);
  */
 void thread_sleep(void);
 
+/**
+ * @brief   The current thread yields and let the scheduler run.
+ */
+void thread_yield(void);
+
 /**
  * @brief   Wakes up a sleeping thread.
  * @param   pid The PID of the thread to be woken up

cpu/arm_common/include/arm_cpu.h

@@ -11,7 +11,6 @@
 extern void dINT(void);
 extern void eINT(void);
 
-void thread_yield(void);
 uint32_t get_system_speed(void);
 void cpu_clock_scale(uint32_t source, uint32_t target, uint32_t *prescale);
 

cpu/native/include/cpu.h

@@ -67,8 +67,5 @@ int register_interrupt(int sig, void (*handler)(void));
  */
 int unregister_interrupt(int sig);
 
-/* this should be defined elsewhere */
-void thread_yield(void);
-
 /** @} */
 #endif //_CPU_H