Fixing gflags' include path.
diff --git a/test/cpp/interop/server.cc b/test/cpp/interop/server.cc
index f4b9f04..8566ad5 100644
--- a/test/cpp/interop/server.cc
+++ b/test/cpp/interop/server.cc
@@ -35,7 +35,7 @@
 #include <sstream>
 #include <thread>
 
-#include <google/gflags.h>
+#include <gflags/gflags.h>
 #include <grpc/grpc.h>
 #include <grpc/support/log.h>
 #include "test/core/end2end/data/ssl_test_data.h"