Fix build for r369374

This patch added some gtest code to the TestingSupport library. As this
is not a unit test, but a unit test library, gtest does not get added to
the include path automatically, but we have to do that ourselves. (It
was working for me without this because the compiler picked up the
system gtest instead.)

llvm-svn: 369381

lldb/unittests/TestingSupport/CMakeLists.txt

@@ -10,3 +10,4 @@ add_lldb_library(lldbUtilityHelpers
     Support
     ObjectYAML
   )
+include_directories(${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest/include)