Remove os_aio_simulated_put_read_threads_to_sleep()

According to the code, it was Windows specific "simulated AIO"
workaround. The simulated s not supported on Windows anymore.

Thus, remove the dead code

storage/innobase/buf/buf0rea.cc

@@ -703,12 +703,6 @@ buf_read_ahead_linear(const page_id_t page_id, ulint zip_size, bool ibuf)
 
 	ulint ibuf_mode = ibuf ? BUF_READ_IBUF_PAGES_ONLY : BUF_READ_ANY_PAGE;
 
-	/* Since Windows XP seems to schedule the i/o handler thread
-	very eagerly, and consequently it does not wait for the
-	full read batch to be posted, we use special heuristics here */
-
-	os_aio_simulated_put_read_threads_to_sleep();
-
 	for (i = low; i < high; i++) {
 		/* It is only sensible to do read-ahead in the non-sync
 		aio mode: hence FALSE as the first parameter */

storage/innobase/include/os0file.h

@@ -1442,17 +1442,6 @@ os_aio_wait_until_no_pending_writes();
 void
 os_aio_simulated_wake_handler_threads();
 
-#ifdef _WIN32
-/** This function can be called if one wants to post a batch of reads and
-prefers an i/o-handler thread to handle them all at once later. You must
-call os_aio_simulated_wake_handler_threads later to ensure the threads
-are not left sleeping! */
-void
-os_aio_simulated_put_read_threads_to_sleep();
-#else /* _WIN32 */
-# define os_aio_simulated_put_read_threads_to_sleep()
-#endif /* _WIN32 */
-
 /** This is the generic AIO handler interface function.
 Waits for an aio operation to complete. This function is used to wait the
 for completed requests. The AIO array of pending requests is divided

storage/innobase/os/os0file.cc

@@ -4693,48 +4693,6 @@ os_file_set_eof(
 	return(SetEndOfFile(h));
 }
 
-/** This function can be called if one wants to post a batch of reads and
-prefers an i/o-handler thread to handle them all at once later. You must
-call os_aio_simulated_wake_handler_threads later to ensure the threads
-are not left sleeping! */
-void
-os_aio_simulated_put_read_threads_to_sleep()
-{
-	AIO::simulated_put_read_threads_to_sleep();
-}
-
-/** This function can be called if one wants to post a batch of reads and
-prefers an i/o-handler thread to handle them all at once later. You must
-call os_aio_simulated_wake_handler_threads later to ensure the threads
-are not left sleeping! */
-void
-AIO::simulated_put_read_threads_to_sleep()
-{
-	/* The idea of putting background IO threads to sleep is only for
-	Windows when using simulated AIO. Windows XP seems to schedule
-	background threads too eagerly to allow for coalescing during
-	readahead requests. */
-
-	if (srv_use_native_aio) {
-		/* We do not use simulated AIO: do nothing */
-
-		return;
-	}
-
-	os_aio_recommend_sleep_for_read_threads	= true;
-
-	for (ulint i = 0; i < os_aio_n_segments; i++) {
-		AIO*	array;
-
-		get_array_and_local_segment(&array, i);
-
-		if (array == s_reads) {
-
-			os_event_reset(os_aio_segment_wait_events[i]);
-		}
-	}
-}
-
 #endif /* !_WIN32*/
 
 /** Does a syncronous read or write depending upon the type specified