devel/jsoncpp: 0.6.0 -> 1.7.2

Changes: https://github.com/open-source-parsers/jsoncpp/releases

• Changed distsite to github
• This is a major upgrade, please report any issues

PR: 209407
Submitted by: yuri@rawbw.com
Approved by: johan@stromnet.se (maintainer)
Reviewed by: brd, swills