todo from Sereal::Decoder

  todo from Sereal::Decoder
 - d/{watch,copyright,control}: replace http://search.cpan.org/dist/ with
    https://metacpan.org/release/
 - d/copyright: BSD-3-clause
 - d/copyright: ppport.h 3 copyright holders
 - d/control:
   + debhelper: >= 9.20120312
   + Standards-Version: 3.9.4
   + perl (>= 5.11.1) | libextutils-parsexs-perl (>= 2.21), perl
   + removed perl 5.6.0
   + fixed description