Bug#57720 - Windows Vista and possibly Windows 7 can return ERROR_TIMEOUT instead of WAIT_TIMEOUT from calls to SleepConditionVariableCS() which is used in os0sync.c; os_cond_wait_timeout() where it is mapped to sleep_condition_variable().   

Consider ERROR_TIMEOUT to be a timeout just like WAIT_TIMEOUT.  

In addition, test for EINTR as a possible return value from pthread_cond_timeout() in the posix section of os_cond_wait_timeout(), even though it is not supposed to be returned, but just to be safe.