fix cygwin build failure unreleased regression

configure.in

@@ -258,9 +258,17 @@ AC_HELP_STRING([--disable-debug],[Disable debug options]),
 AC_CHECK_HEADERS([errno.h fcntl.h stdio.h stdlib.h unistd.h sys/uio.h])
 AC_CHECK_HEADERS([sys/select.h sys/socket.h sys/ioctl.h sys/time.h])
 AC_CHECK_HEADERS([arpa/inet.h netinet/in.h])
-AC_CHECK_HEADERS([windows.h winsock2.h ws2tcpip.h])
 AC_CHECK_FUNCS(poll gettimeofday select strtoll)
 
+case $host in
+  *-*-cygwin* | *-*-cegcc*)
+    # These are POSIX-like systems using BSD-like sockets API.
+    ;;
+  *)
+    AC_CHECK_HEADERS([windows.h winsock2.h ws2tcpip.h])
+    ;;
+esac
+
 dnl Check for select() into ws2_32 for Msys/Mingw
 if test "$ac_cv_func_select" != "yes"; then
   AC_MSG_CHECKING([for select in ws2_32])