[CMake] Don't include the test directories if CLANG_INCLUDE_TESTS is Off

This matches Clang's behavior.

git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@249048 91177308-0d34-0410-b5e6-96231b3b80d8

CMakeLists.txt

@@ -12,7 +12,7 @@ add_subdirectory(tool-template)
 
 # Add the common testsuite after all the tools.
 # TODO: Support tests with more granularity when features are off?
-if(CLANG_ENABLE_STATIC_ANALYZER)
+if(CLANG_ENABLE_STATIC_ANALYZER AND CLANG_ENABLE_TESTS)
 add_subdirectory(test)
 add_subdirectory(unittests)
 endif()