Correcting reference to policy version

CMakeLists.txt

@@ -22,7 +22,7 @@ cmake_minimum_required(VERSION 2.8.9)
 
 foreach(p
   CMP0054 # CMake 3.1
-  CMP0020 # CMake 3.0.2
+  CMP0020 # CMake 2.8.11
   )
   if(POLICY ${p})
     cmake_policy(SET ${p} NEW)