Set cmake policy CMP0069

This ensures that LTO works as expected whenever the main project
has it enabled.

Author: Krzmbrzl

CMakeLists.txt

@@ -11,6 +11,10 @@ if (POLICY CMP0077)
   cmake_policy(SET CMP0077 NEW)
 endif (POLICY CMP0077)
 
+if (POLICY CMP0069)
+  cmake_policy(SET CMP0069 NEW)
+endif (POLICY CMP0069)
+
 project(googletest-distribution)
 set(GOOGLETEST_VERSION 1.11.0)