devel/jsoncpp: Update to 1.9.8

• Change install dir to match other major (Linux) distros
• Some small adjustments port Makefile to closer follow Porters Handbook
• Import patch from Debian, prefer shared library over static

Changelog:
https://github.com/open-source-parsers/jsoncpp/releases/tag/1.9.8

Reference:
https://sources.debian.org/patches/libjsoncpp/1.9.8-2/0001-Prefer-shared-library-for-namespaced-target.patch/

PR: 297570
Approved by: maintainer timeout, 2+ weeks