* cygwin.din (pthread_yield): Export as alias to sched_yield.

* include/pthread.h (pthread_yield): Declare.
* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Bump.
* posix.sgml (std-deprec): Add pthread_yield.

winsup/cygwin/include/pthread.h

@@ -194,6 +194,7 @@ void pthread_testcancel (void);
 
 int pthread_suspend (pthread_t);
 int pthread_continue (pthread_t);
+int pthread_yield (void);
 
 #ifdef __cplusplus
 }