7ef62e14a5c519b7b7e9c8bed1931d0cfeacbca6 Revert "trust_region/dogleg: fixing sign error"

================================ DYNARE MAKE CHECK MATLAB RESULTS ================================ | TOTAL: 423 | PASS: 421 | FAIL: 0 | XFAIL: 2 | XPASS: 0

================================ DYNARE MAKE CHECK OCTAVE RESULTS ================================ | TOTAL: 421 | PASS: 419 | FAIL: 0 | XFAIL: 2 | XPASS: 0

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