Refactor configure script detection of functions used to set sockets into

non-blocking mode, and decouple function detection from function capability.

acinclude.m4

@@ -1965,154 +1965,6 @@ AC_DEFUN([TYPE_SIG_ATOMIC_T], [
 ])
 
 
-dnl CURL_CHECK_NONBLOCKING_SOCKET
-dnl -------------------------------------------------
-dnl Check for how to set a socket to non-blocking state. There seems to exist
-dnl four known different ways, with the one used almost everywhere being POSIX
-dnl and XPG3, while the other different ways for different systems (old BSD,
-dnl Windows and Amiga).
-dnl
-dnl There are two known platforms (AIX 3.x and SunOS 4.1.x) where the
-dnl O_NONBLOCK define is found but does not work. This condition is attempted
-dnl to get caught in this script by using an excessive number of #ifdefs...
-
-AC_DEFUN([CURL_CHECK_NONBLOCKING_SOCKET], [
-  AC_MSG_CHECKING([non-blocking sockets style])
-  nonblock="unknown"
-  #
-  AC_COMPILE_IFELSE([
-    AC_LANG_PROGRAM([[
-/* headers for O_NONBLOCK test */
-#include <sys/types.h>
-#include <unistd.h>
-#include <fcntl.h>
-/* */
-#if defined(sun) || defined(__sun__) || \
-    defined(__SUNPRO_C) || defined(__SUNPRO_CC)
-# if defined(__SVR4) || defined(__srv4__)
-#  define PLATFORM_SOLARIS
-# else
-#  define PLATFORM_SUNOS4
-# endif
-#endif
-#if (defined(_AIX) || defined(__xlC__)) && !defined(_AIX41)
-# define PLATFORM_AIX_V3
-#endif
-/* */
-#if defined(PLATFORM_SUNOS4) || defined(PLATFORM_AIX_V3) || defined(__BEOS__)
-#error "O_NONBLOCK does not work on this platform"
-#endif
-    ]],[[
-      /* O_NONBLOCK source test */
-      int socket;
-      int flags = fcntl(socket, F_SETFL, flags | O_NONBLOCK);
-    ]])
-  ],[
-    dnl the O_NONBLOCK test was fine
-    nonblock="O_NONBLOCK"
-    AC_DEFINE(HAVE_O_NONBLOCK, 1,
-      [use O_NONBLOCK for non-blocking sockets])
-  ])
-  #
-  if test "$nonblock" = "unknown"; then
-    AC_COMPILE_IFELSE([
-      AC_LANG_PROGRAM([[
-/* headers for FIONBIO test */
-#include <unistd.h>
-#include <stropts.h>
-      ]],[[
-        /* FIONBIO source test (old-style unix) */
-        int socket;
-        int flags = ioctl(socket, FIONBIO, &flags);
-      ]])
-    ],[
-      dnl FIONBIO test was good
-      nonblock="FIONBIO"
-      AC_DEFINE(HAVE_FIONBIO, 1,
-        [use FIONBIO for non-blocking sockets])
-    ])
-  fi
-  #
-  if test "$nonblock" = "unknown"; then
-    AC_COMPILE_IFELSE([
-      AC_LANG_PROGRAM([[
-/* headers for ioctlsocket test (Windows) */
-#undef inline
-#ifdef HAVE_WINDOWS_H
-#ifndef WIN32_LEAN_AND_MEAN
-#define WIN32_LEAN_AND_MEAN
-#endif
-#include <windows.h>
-#ifdef HAVE_WINSOCK2_H
-#include <winsock2.h>
-#else
-#ifdef HAVE_WINSOCK_H
-#include <winsock.h>
-#endif
-#endif
-#endif
-      ]],[[
-        /* ioctlsocket source code (Windows) */
-        SOCKET sd;
-        unsigned long flags = 0;
-        sd = socket(0, 0, 0);
-        ioctlsocket(sd, FIONBIO, &flags);
-      ]])
-    ],[
-      dnl ioctlsocket test was good
-      nonblock="ioctlsocket"
-      AC_DEFINE(HAVE_IOCTLSOCKET, 1,
-        [use ioctlsocket() for non-blocking sockets])
-    ])
-  fi
-  #
-  if test "$nonblock" = "unknown"; then
-    AC_LINK_IFELSE([
-      AC_LANG_PROGRAM([[
-/* headers for IoctlSocket test (Amiga?) */
-#include <sys/ioctl.h>
-      ]],[[
-        /* IoctlSocket source code (Amiga?) */
-        int socket;
-        int flags = IoctlSocket(socket, FIONBIO, (long)1);
-      ]])
-    ],[
-      dnl Ioctlsocket test was good
-      nonblock="IoctlSocket"
-      AC_DEFINE(HAVE_IOCTLSOCKET_CASE, 1,
-        [use Ioctlsocket() for non-blocking sockets])
-    ])
-  fi
-  #
-  if test "$nonblock" = "unknown"; then
-    AC_COMPILE_IFELSE([
-      AC_LANG_PROGRAM([[
-/* headers for SO_NONBLOCK test (BeOS) */
-#include <socket.h>
-      ]],[[
-        /* SO_NONBLOCK source code (BeOS) */
-        long b = 1;
-        int socket;
-        int flags = setsockopt(socket, SOL_SOCKET, SO_NONBLOCK, &b, sizeof(b));
-      ]])
-    ],[
-      dnl the SO_NONBLOCK test was good
-      nonblock="SO_NONBLOCK"
-      AC_DEFINE(HAVE_SO_NONBLOCK, 1,
-        [use SO_NONBLOCK for non-blocking sockets])
-    ])
-  fi
-  #
-  AC_MSG_RESULT($nonblock)
-  #
-  if test "$nonblock" = "unknown"; then
-    AC_DEFINE(HAVE_DISABLED_NONBLOCKING, 1,
-      [disabled non-blocking sockets])
-    AC_MSG_WARN([non-block sockets disabled])
-  fi
-])
-
-
 dnl TYPE_IN_ADDR_T
 dnl -------------------------------------------------
 dnl Check for in_addr_t: it is used to receive the return code of inet_addr()