Improve threading and i/o routines

- On Windows connect() can now be interrupted by a signal; connect() w/
  O_NONBLOCK will now raise EINPROGRESS; and connect() with SO_SNDTIMEO
  will raise ETIMEDOUT after the interval has elapsed.

- We now get the AcceptEx(), ConnectEx(), and TransmitFile() functions
  from the WIN32 API the officially blessed way, using WSAIoctl().

- Do nothing on Windows when fsync() is called on a directory handle.
  This was raising EACCES earlier becaues GENERIC_WRITE is required on
  the handle. It's possible to FlushFileBuffers() a directory handle if
  it's opened with write access but MSDN doesn't document what it does.
  If you have any idea, please let us know!

- Prefer manual reset event objects for read() and write() on Windows.

- Do some code cleanup on our dlmalloc customizations.

- Fix errno type error in Windows blocking routines.

- Make the futex polyfill simpler and faster.

libc/nt/master.sh

@@ -483,15 +483,6 @@ imp	'GetSaveFileName'					GetSaveFileNameW					comdlg32	1
 imp	'PrintDlg'						PrintDlgW						comdlg32	1
 imp	'ReplaceText'						ReplaceTextW						comdlg32	1
 
-# MSWSOCK.DLL
-#
-#	Name							Actual							DLL		Arity
-imp	'AcceptEx'						AcceptEx						MsWSock		8
-imp	'DisconnectEx'						DisconnectEx						MsWSock		4
-imp	'GetAcceptExSockaddrs'					GetAcceptExSockaddrs					MsWSock		8
-imp	'TransmitFile'						TransmitFile						MsWSock		7
-imp	'WSARecvEx'						WSARecvEx						MsWSock		4
-
 # WS2_32.DLL
 #
 #	Name							Actual							DLL		Arity
@@ -516,6 +507,7 @@ imp	''							setsockopt						ws2_32		5
 imp	''							shutdown						ws2_32		2
 imp	''							socket							ws2_32		3
 imp	''							socket							ws2_32		3
+imp	''							socket							ws2_32		3
 imp	'FreeAddrInfo'						FreeAddrInfoW						ws2_32		1
 imp	'FreeAddrInfoEx'					FreeAddrInfoExW						ws2_32		1
 imp	'GetAddrInfo'						GetAddrInfoW						ws2_32		4