Tests/RunCMake: Tell cmake not to report unused command-line options

On OS X we pass -DCMAKE_POLICY_DEFAULT_CMP0025=NEW to all tests.
Once tests start using cmake_minimum_required(VERSION 3.0) then
CMake will warn that CMAKE_POLICY_DEFAULT_CMP0025 is unused.
These warnings are not part of the expected test output and can
cause such tests to fail.  Pass --no-warn-unused-cli to each test
cmake invocation to tell it not to produce these warnings.

Tests/RunCMake/RunCMake.cmake

@@ -53,6 +53,7 @@ function(run_cmake test)
                 -G "${RunCMake_GENERATOR}"
                 -T "${RunCMake_GENERATOR_TOOLSET}"
                 -DRunCMake_TEST=${test}
+                --no-warn-unused-cli
                 ${RunCMake_TEST_OPTIONS}
       WORKING_DIRECTORY "${RunCMake_TEST_BINARY_DIR}"
       OUTPUT_VARIABLE actual_stdout