do not redefine stl logging macros
diff --git a/src/stl_logging_unittest.cc b/src/stl_logging_unittest.cc
index 20f23b3..63e28a1 100644
--- a/src/stl_logging_unittest.cc
+++ b/src/stl_logging_unittest.cc
@@ -41,11 +41,19 @@
// C++0x isn't enabled by default in GCC and libc++ does not have
// non-standard ext/* and tr1/unordered_*.
# if defined(_LIBCPP_VERSION)
+# ifndef GLOG_STL_LOGGING_FOR_UNORDERED
# define GLOG_STL_LOGGING_FOR_UNORDERED
+# endif
# else
+# ifndef GLOG_STL_LOGGING_FOR_EXT_HASH
# define GLOG_STL_LOGGING_FOR_EXT_HASH
+# endif
+# ifndef GLOG_STL_LOGGING_FOR_EXT_SLIST
# define GLOG_STL_LOGGING_FOR_EXT_SLIST
+# endif
+# ifndef GLOG_STL_LOGGING_FOR_TR1_UNORDERED
# define GLOG_STL_LOGGING_FOR_TR1_UNORDERED
+# endif
# endif
#endif