+ AC_SYS_LARGEFILE_MACRO_VALUE(_XOPEN_SOURCE,
+ ac_cv_sys_xopen_source,
+ [Define to make ftello visible on some hosts (e.g. glibc 2.1.3).],
+ [AC_TRY_COMPILE([#include <stdio.h>], [return !ftello;], ,
+ [AC_TRY_COMPILE([#define _XOPEN_SOURCE 500
+#include <stdio.h>],
+ [return !ftello;],
+ ac_cv_sys_xopen_source=500)])])