Copyright for arpack++ source package in Buster

Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
Upstream-Name: ARPACK++
Source: http://www.caam.rice.edu/software/ARPACK/arpack++.html

Files: *
Copyright: 2003 Christophe Prud'homme (prudhomm@debian.org)
License: public-domain
  Public domain software.