5b6e3bdb7a11612c8bd8d6c6d198a2eac94e2766 Fix bug in simul with stack_solve_algo=0 and exogenous with lags > 1

================================ DYNARE MAKE CHECK MATLAB RESULTS ================================ | TOTAL: 200 | PASS: 198 | FAIL: 1 | XFAIL: 1 | XPASS: 0 | LIST OF FAILED TESTS: | * gsa/ls2003.mod

================================ DYNARE MAKE CHECK OCTAVE RESULTS ================================ | TOTAL: 198 | PASS: 196 | FAIL: 1 | XFAIL: 1 | XPASS: 0 | LIST OF FAILED TESTS: | * gsa/ls2003.mod

A full log can be found on karaba in '/tmp/dynare-master-check-1weVZO8KvN.log'.