cmake/sanitizer.cmake: fixed to be CMake 3.8 compliant

cmake/sanitizer.cmake

@@ -21,7 +21,8 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" OR CMAKE_CXX_COMPILER_ID STREQUAL "Clang
       list(APPEND libClaPP_SANITIZERS "thread")
     endif()
 
-    list(JOIN libClaPP_SANITIZERS "," libClaPP_LIST_OF_SANITIZERS)
+    set(libClaPP_LIST_OF_SANITIZERS ${libClaPP_SANITIZERS})
+    string(REPLACE ";" "," libClaPP_LIST_OF_SANITIZERS "${libClaPP_LIST_OF_SANITIZERS}")
 endif()
 
 if(libClaPP_LIST_OF_SANITIZERS)