CMake: Fix warning in gtest header used by unit tests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121127 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/CMakeLists.txt b/unittests/CMakeLists.txt
index 4ae9d63..f3de834 100644
--- a/unittests/CMakeLists.txt
+++ b/unittests/CMakeLists.txt
@@ -22,6 +22,10 @@
   add_definitions(-DGTEST_HAS_PTHREAD=0)
 endif()
 
+if(SUPPORTS_NO_VARIADIC_MACROS_FLAG)
+  add_definitions("-Wno-variadic-macros")
+endif()
+
 set(LLVM_LINK_COMPONENTS
   jit
   interpreter