g-soccon.ads: Add new constant Thread_Blocking_IO...

g-soccon.ads: Add new constant Thread_Blocking_IO...

2007-04-20  Thomas Quinot  <quinot@adacore.com>

	* g-soccon.ads: Add new constant Thread_Blocking_IO, always True by
	default, set False on a per-runtime basis.
	(Need_Netdb_Buffer): New constant.

	* g-socket.ads, g-socket.adb: Import new package
	GNAT.Sockets.Thin.Task_Safe_NetDB.
	(Raise_Host_Error): Use Host_Error_Message from platform-specific thin
	binding to obtain proper message.
	(Close_Selector): Use GNAT.Sockets.Thin.Signalling_Fds.Close.
	Replace various occurrences of Arry (Arry'First)'Address with the
	equivalent Arry'Address (GNAT always follows implementation advice from
	13.3(14)).
	(Get_Host_By_Address, Get_Host_By_Name,
	Get_Service_By_Name, Get_Service_By_Port): Do not use GNAT.Task_Lock;
	instead, rely on platform-specific task safe netdb operations provided
	by g-socthi.

	* g-socthi.ads, g-socthi.adb (Initialize): Remove obsolete formal
	parameter Process_Blocking_IO.
	(Host_Error_Messages): Add stub body.
	(GNAT.Sockets.Thin.Signalling_Fds): New procedure Close.
	(Safe_Gethostbyname, Safe_Gethostbyaddr, Safe_Getservbyname,
	Safe_Getservbyport): Move functions into new child package
	Task_Safe_NetDB.
	(Nonreentrant_Gethostbyname, Nonreentrant_Gethostbyaddr,
	Nonreentrant_Getservbyname, Nonreentrant_Getservbyport): New routines.
	(In_Addr): Add alignment clause.

From-SVN: r125424