fix gcc 9.1.1 compile warnings Use snprintf instead of strncpy to ensure NUL termination. Simplify attribute copying to calloc/memcpy instead of malloc/memset/strncpy/assignment. Appeases gcc 9.1.1 warnings about strncpy bounds.

The digested changelog can be found under:
 contrib/debian/changelog
 
You can also find the exhaustive list of change using mercurial history, 
or at the following URL: http://www.freediameter.net/hg/freeDiameter/shortlog