Prevent some compilers compaining unused return value

test/cpp/util/byte_buffer_proto_helper.cc

@@ -38,7 +38,7 @@ namespace testing {
 
 bool ParseFromByteBuffer(ByteBuffer* buffer, grpc::protobuf::Message* message) {
   std::vector<Slice> slices;
-  buffer->Dump(&slices);
+  (void)buffer->Dump(&slices);
   grpc::string buf;
   buf.reserve(buffer->Length());
   for (auto s = slices.begin(); s != slices.end(); s++) {

test/cpp/util/byte_buffer_test.cc

@@ -100,7 +100,7 @@ TEST_F(ByteBufferTest, Dump) {
   slices.push_back(Slice(world, Slice::STEAL_REF));
   ByteBuffer buffer(&slices[0], 2);
   slices.clear();
-  buffer.Dump(&slices);
+  (void)buffer.Dump(&slices);
   EXPECT_TRUE(SliceEqual(slices[0], hello));
   EXPECT_TRUE(SliceEqual(slices[1], world));
 }

test/cpp/util/cli_call.cc

@@ -94,7 +94,7 @@ Status CliCall::Call(std::shared_ptr<grpc::Channel> channel,
 
   if (status.ok()) {
     std::vector<grpc::Slice> slices;
-    recv_buffer.Dump(&slices);
+    (void)recv_buffer.Dump(&slices);
 
     response->clear();
     for (size_t i = 0; i < slices.size(); i++) {