CFLAGS="-Wall -Wextra -Wconversion $CFLAGS"
fi
-AC_CHECK_HEADERS([fcntl.h error.h])
+AC_CHECK_HEADERS([error.h])
+AC_CHECK_HEADERS([fcntl.h],
+ [],[AC_MSG_ERROR([header is required])])
AC_TYPE_PID_T
AC_TYPE_SIZE_T
AC_C_INLINE
AX_C___ATTRIBUTE__
+AC_CHECK_MEMBER([struct _IO_FILE._fileno],
+ [AC_DEFINE([HAVE_STRUCT__IO_FILE__FILENO], 1,
+ [Define to 1 if `_fileno' is a member of `struct _IO_FILE'.])],
+ [],[[#include <libio.h>]])
+
AC_FUNC_FORK
AC_CHECK_FUNCS([memmove setenv],
[],[AC_MSG_ERROR([function is required])])