CID 1508860: Double lock

[maskit]

AIO.cc

529      if (op->thread == AIO_CALLBACK_THREAD_AIO) {
530        SCOPED_MUTEX_LOCK(lock, op->mutex, thr_info->mutex->thread_holding);
531        op->handleEvent(EVENT_NONE, nullptr);
   	12. Falling through to end of if statement.
   	24. Falling through to end of if statement.
   	37. Condition op->thread == NULL, taking true branch.
532      } else if (op->thread == AIO_CALLBACK_THREAD_ANY) {
533        eventProcessor.schedule_imm(op);
   	38. Falling through to end of if statement.
534      } else {
535        op->thread->schedule_imm(op);
536      }
   	25. lock: ink_mutex_acquire locks my_aio_req->aio_mutex. [[show details](https://scan6.scan.coverity.com/eventId=34764104-39&modelId=34764104-0&fileInstanceId=164784741&filePath=%2Finclude%2Ftscore%2Fink_mutex.h&fileStart=46&fileEnd=52)]
   	
CID 1508860 (#1-2 of 2): Double lock (LOCK)
39. double_lock: ink_mutex_acquire locks my_aio_req->aio_mutex while it is locked.
537      ink_mutex_acquire(&my_aio_req->aio_mutex);