implement full-blown select(2) for winsock

implement full-blown select(2) for winsock

2008-09-24  Paolo Bonzini  <bonzini@gnu.org>

	* NEWS: Document increased portability that sys_select now provides.

	* lib/sys_select.in.h: Install select wrapper.
	* lib/sys_socket.in.h: Use more descriptive name when there is no
	select wrapper.
	* lib/winsock-select.c: New.
	* m4/sys_select_h.m4: Compile lib/winsock-select.c if WinSock is used.
	Require gl_HEADER_SYS_SOCKET.
	* modules/sys_select: Depend on alloca, add lib/winsock-select.c.
	* modules/sys_select-tests: Copy dependencies from modules/poll-tests.
	* tests/test-sys_select.c: Add functional tests.