support posix

1. posix pthread.h: pthread, pthread_barrier, pthread_cond, pthread_mutex, , pthread_rwlock, pthread_spin, etc
2. posix semaphore.h: sem_*
3. posix mqueue.h: mq_*
4. posix time.h: timer_*
5. to support posix, add tos_barrier, tos_bitmap, tos_rwlock, tos_stopwatch, change name of k_task_t from a char * pointer to a char array.
6. sample, see examples\posix
7. project, see board\TencentOS_tiny_EVB_MX_Plus\KEIL\posix

kernel/core/include/tos_time.h

@@ -18,6 +18,8 @@
 #ifndef _TOS_TIME_H_
 #define  _TOS_TIME_H_
 
+__CDECLS_BEGIN
+
 // if you wanna pend for something forever, use TOS_TIME_FOREVER
 #define TOS_TIME_FOREVER            (k_tick_t)(-1)
 // if you don't wanna wait when you pend nothing, use TOS_TIME_NOWAIT
@@ -106,5 +108,7 @@ __API__ k_err_t     tos_sleep_ms(k_time_t millisec);
  */
 __API__ k_err_t     tos_sleep_hmsm(k_time_t hour, k_time_t minute, k_time_t second, k_time_t millisec);
 
+__CDECLS_END
+
 #endif /* _TOS_TIME_H_ */