# Sets and substitutes HAVE_WINSOCK2_H.
AC_DEFUN([gl_PREREQ_SYS_H_WINSOCK2],
[
- AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
- AC_REQUIRE([gl_SYS_IOCTL_H_DEFAULTS])
+ m4_ifdef([gl_UNISTD_H_DEFAULTS], [AC_REQUIRE([gl_UNISTD_H_DEFAULTS])])
+ m4_ifdef([gl_SYS_IOCTL_H_DEFAULTS], [AC_REQUIRE([gl_SYS_IOCTL_H_DEFAULTS])])
AC_CHECK_HEADERS_ONCE([sys/socket.h])
if test $ac_cv_header_sys_socket_h != yes; then
dnl We cannot use AC_CHECK_HEADERS_ONCE here, because that would make