Add it to a private source directory that is not installed so that we
can use it for building CMake itself. This will allow it to mature
before being distributed publicly.
Since jsoncpp 0.7.0 (2014-11-20) the upstream may provide a CMake
package configuration file such that find_package(jsoncpp) will find a
jsoncppConfig.cmake file. In order to avoid conflicting with this
(especially on case-insensitive filesystems), and since we always prefer
projects to provide package config files (that they maintain), it is
better to not provide FindJsonCpp publicly.
Move FindJsonCpp into a private source directory that is not installed
so that we can still use it for building CMake itself.
Reported-by: Ryan Pavlik <ryan.pavlik@gmail.com>
Brad King