f8f186792138e373b51e6dad0d28f48786ddbb6a build system: add flag for mex compilation on OS X 10.9

================================ 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-zgidrGRxBl.log'.