diff -up octave-4.2.0/m4/link.m4.implicit octave-4.2.0/m4/link.m4
--- octave-4.2.0/m4/link.m4.implicit	2016-11-13 08:21:54.000000000 -0700
+++ octave-4.2.0/m4/link.m4	2016-12-06 13:52:47.132003993 -0700
@@ -22,6 +22,7 @@ AC_DEFUN([gl_FUNC_LINK],
        AC_RUN_IFELSE(
          [AC_LANG_PROGRAM(
            [[#include <unistd.h>
+             #include <stdio.h>
            ]],
            [[int result = 0;
              if (!link ("conftest.a", "conftest.b/"))