CMake includes grabbed from project-relative path.

CMakeLists.txt

@@ -25,8 +25,8 @@ project("Eclipse Paho C"
 message(STATUS "CMake version: " ${CMAKE_VERSION})
 message(STATUS "CMake system name: " ${CMAKE_SYSTEM_NAME})
 
-set(CMAKE_SCRIPTS "${CMAKE_SOURCE_DIR}/cmake")
-set(CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/modules")
+set(CMAKE_SCRIPTS "${PROJECT_SOURCE_DIR}/cmake")
+set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/modules")
 
 ## Project Version
 ## Previously we read in the version from these files, but now we use the