[Ipopt] Ipopt maintenance release 3.12.4

[Stefan Vigerske]

Hi,

I just created a new Ipopt maintenance release.
If you were using a recent Ipopt version successfully, then there is no 
need to update.

Here is a list of changes:
- fix to use regularized Hessian when doing a curvature test without
   ineration information (neg_curv_test_tol > 0), new option
   neg_curv_test_reg to switch back to original behavior
   (by N.-Y. Chang and V. Zavala Tejeda)
- sIpopt: Added access to sensitivity directional derivative
   vector (ds/dp*(p-p0) Eq. 14 sIpopt implementation paper). Also,
   added an option to compute the sensitivity matrix and provide
   access to it. Finally, added an example that shows how to
   access the new information. (by R. Lopez-Negrete)
- use workaround for failing check for random number generator
   with any gcc 4.8.x (x >= 2), not only 4.8.3
- fix LD setting when using ifort on non-Windows system

The source tarballs should be available tomorrow.

Enjoy,
Stefan