Silence warning in CMake 2.8.12 and later


git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1151 632fc199-4ca6-4c93-a231-07263d6284db
diff --git a/CMakeLists.txt b/CMakeLists.txt
index f88cf4f..d80933e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,7 @@
 #
 
 cmake_minimum_required(VERSION 2.8.8)
+cmake_policy(SET CMP0022 OLD)
 
 project(libjpeg-turbo C)
 set(VERSION 1.3.80)