28054c46dc2f379a502a7c9f82d4d897f4513b48 removed useless test with exist() that is very expensive in Octave (but apparently not in Matlab)

================================ DYNARE MAKE CHECK MATLAB RESULTS ================================ | TOTAL: 417 | PASS: 415 | FAIL: 0 | XFAIL: 2 | XPASS: 0

================================ DYNARE MAKE CHECK OCTAVE RESULTS ================================ | TOTAL: 415 | PASS: 413 | FAIL: 0 | XFAIL: 2 | XPASS: 0

A full log can be found on karaba in '/tmp/dynare-4.4-check-J9B5bzzclt.log'.