Update mplapack-interop index to 0.5.1

[nakatamaho]

Summary

• Add the released mplapack-interop 0.5.1 archive as the recommended version while retaining 0.5.0 in the history.
• Update the pinned license and documentation links to v0.5.1.

Release archive: https://github.com/nakatamaho/octave-mplapack/releases/download/v0.5.1/mplapack-interop-0.5.1.tar.gz
SHA256: 50622b177d9e320ad8c02d4c15aae037a0643c27300a5ead529f4e829ad8d080

MPC 1.3.1 compatibility

MPC 1.3.1, available in Ubuntu 26.04, does not provide the mpc_log2 symbol. The 0.5.1 release removes the direct mpc_log2 dependency for complex log2 and uses the gmpfrxx compatibility implementation instead, allowing this path to work with MPC 1.3.1.

CI dependency note

The existing Ubuntu dependency libmplapack-mpfr-dev is unchanged. It is not yet available in the standard Ubuntu repositories used by package-index CI, so the package-install check remains blocked until that dependency is packaged. This limitation was discussed and accepted in #841; the installation check should be rerun when the dependency becomes available.

Local yamllint and validate_yaml.py checks pass. Related: #841.

[nakatamaho]

Thanks, Markus, for merging #844 and updating the mplapack-interop entry to version 0.5.1. I really appreciate your help and your work maintaining the Octave Packages index!