ilu function has been implemented in Octave 4.0.

(manually cherry picked from commit 80f512b9)

matlab/dynare_config.m

@@ -90,8 +90,8 @@ if ~isoctave && matlab_ver_less_than('7.4')
     addpath([dynareroot '/missing/bsxfun'])
 end
 
-% ilu is missing in old versions of MATLAB and in Octave
-if isoctave || matlab_ver_less_than('7.4')
+% ilu is missing in old versions of MATLAB and in Octave < 4.0
+if (isoctave && octave_ver_less_than('4.0')) || matlab_ver_less_than('7.4')
     addpath([dynareroot '/missing/ilu'])
 end