Update CMake build for new gtest file.

llvm-svn: 136215
diff --git a/llvm/utils/unittest/CMakeLists.txt b/llvm/utils/unittest/CMakeLists.txt
index 29218bb..73491f0 100644
--- a/llvm/utils/unittest/CMakeLists.txt
+++ b/llvm/utils/unittest/CMakeLists.txt
@@ -32,6 +32,7 @@
   googletest/gtest-death-test.cc
   googletest/gtest-filepath.cc
   googletest/gtest-port.cc
+  googletest/gtest-printers.cc
   googletest/gtest-test-part.cc
   googletest/gtest-typed-test.cc
   )