FindBoost: Add check for json component header in Boost 1.75+
When support for Boost 1.75 was added, the new JSON component wasn't added to the list of checks for the headers. Without the check, cmake emits an error like the following if "json" is in the components to search for:
-- Found Boost: /usr/include/boost-1_76 (found suitable exact version "1.76.0") found components: filesystem regex program_options unit_test_framework system json container
CMake Warning at /usr/lib64/share/cmake/Modules/FindBoost.cmake:2185 (message):
No header defined for json; skipping header check (note: header-only
libraries have no designated component)
Call Stack (most recent call first):
cmake/ExternalLibraries.cmake:25 (find_package)
CMakeLists.txt:33 (include)
Backport: release
Topic-rename: FindBoost-json-header
Edited by Brad King