relocation of install-include directory for other packages

CMakeLists.txt

@@ -31,7 +31,8 @@ endif()
 include(CMakePackageConfigHelpers)
 configure_package_config_file("cmake/config.cmake.in"
     "${CMAKE_CURRENT_BINARY_DIR}/${JSON_CONFIG_FILENAME}"
-    INSTALL_DESTINATION ${JSON_CONFIG_DESTINATION})
+    INSTALL_DESTINATION ${JSON_CONFIG_DESTINATION}
+    PATH_VARS JSON_INCLUDE_DESTINATION)
 write_basic_package_version_file("${CMAKE_CURRENT_BINARY_DIR}/${JSON_CONFIGVERSION_FILENAME}"
     VERSION ${PROJECT_VERSION}
     COMPATIBILITY SameMajorVersion)

cmake/config.cmake.in

 @PACKAGE_INIT@
+set_and_check(JSON_INCLUDE_DIR "@PACKAGE_JSON_INCLUDE_DESTINATION@")
 
 cmake_policy(PUSH)
 cmake_policy(SET CMP0024 OLD)
 include(${CMAKE_CURRENT_LIST_DIR}/@JSON_TARGETS_FILENAME@)
-cmake_policy(POP)
\ No newline at end of file
+cmake_policy(POP)