- Update to version 1.5.3:
* Added dependency on statistics package.
* Some bug fixes and build fixes for Octave 4.4.
* Unit test for nlinfit is now reproducible.
* Added unit tests in nonlin_residmin and nonlin_curvefit.
* Default algorithm of `nonlin_min' is now more robust.
* Standalone function `samin' is deprecated. The functionality
has been moved into a `samin' backend of function
`nonlin_min'.
- Drop optim-gcc-warnings.patch: incorporated upstream.