Remove the explicit setting of CMP0017, partially undoing #1720.

In master, it's already set to NEW, since we declare the minimal CMake
version as 2.8.7, which is newer than the policy.

CMakeLists.txt

@@ -32,10 +32,6 @@ else(NOT CMAKE_TOOLCHAIN_FILE)
 endif(NOT CMAKE_TOOLCHAIN_FILE)
 
 
-if(POLICY CMP0017)
-  cmake_policy(SET CMP0017 NEW)
-endif()
-
 if(POLICY CMP0022)
   cmake_policy(SET CMP0022 OLD)
 endif()