move to new build system

cmake/libraries/json.cmake

@@ -0,0 +1,35 @@
+if(PROJECT_ENABLE_JSON)
+  if(PROJECT_BUILD)
+    find_package(nlohmann_json ${JSON_VERSION} REQUIRED)
+
+    add_definitions(-DPROJECT_ENABLE_JSON)
+
+    if(PROJECT_IS_MINGW AND PROJECT_IS_MINGW_UNIX)
+      include_directories(BEFORE SYSTEM
+        /mingw64/include/nlohmann
+      )
+    else()
+      include_directories(BEFORE SYSTEM
+        ${PROJECT_EXTERNAL_BUILD_ROOT}/include/nlohmann
+      )
+    endif()
+  elseif(NOT PROJECT_IS_MINGW OR CMAKE_HOST_WIN32)
+    ExternalProject_Add(json_project
+      PREFIX external
+      URL ${PROJECT_3RD_PARTY_DIR}/json-${JSON_VERSION}.tar.gz
+      URL_HASH SHA256=0d8ef5af7f9794e3263480193c491549b2ba6cc74bb018906202ada498a79406
+      LIST_SEPARATOR |
+      CMAKE_ARGS ${PROJECT_EXTERNAL_CMAKE_FLAGS}
+        -DBUILD_SHARED_LIBS=${PROJECT_BUILD_SHARED_LIBS}
+        -DBUILD_STATIC_LIBS=ON
+        -DJSON_BuildTests=OFF
+        -DJSON_Install=ON
+        -DJSON_MultipleHeaders=OFF
+    )
+
+    set(PROJECT_DEPENDENCIES 
+      ${PROJECT_DEPENDENCIES}
+      json_project
+    )
+  endif()
+endif()