Tests: Prevent the noisy CMP0114 warnings in ExternalProjectUpdate test

Tests/ExternalProjectUpdate/CMakeLists.txt

@@ -2,6 +2,11 @@ cmake_minimum_required(VERSION 2.8.12)
 project(ExternalProjectUpdateTest NONE)
 if(CMAKE_XCODE_BUILD_SYSTEM VERSION_GREATER_EQUAL 12)
   cmake_policy(SET CMP0114 NEW)
+else()
+  # This test is very noisy with warnings about this policy if we don't
+  # explicitly set it. Projects shouldn't do this, but for test code this
+  # is reasonable.
+  cmake_policy(SET CMP0114 OLD)
 endif()
 cmake_policy(GET CMP0114 cmp0114)