More correct fix for CMake breakage I was seeing, my buildbots use
LLVM_INCLUDE_TESTS:=OFF, which may no longer be necessary for all I know.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@125985 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 63b7213..0d923b9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -215,7 +215,9 @@
 add_subdirectory(runtime)
 
 # TODO: docs.
+if( LLVM_INCLUDE_TESTS )
 add_subdirectory(test)
+endif()
 
 # FIXME: unittests require gtest.
 if( NOT CLANG_BUILT_STANDALONE )