libstdc++: use std::make_pair to initialize std::pair

|pending_messages_| is std::vector of std::pair values.
libstdc++ does not allow to initialize std::pair with
std::make_tuple(), use std::make_pair() instead.

Bug: 957519
Change-Id: I822b379b34f2973c0ce9704b73370b1e2dc15a9b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2621816Reviewed-by: Kim Paulhamus <kpaulhamus@chromium.org>
Commit-Queue: Kim Paulhamus <kpaulhamus@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842516}

device/fido/cable/v2_test_util.cc

@@ -170,7 +170,7 @@ class TestNetworkContext : public network::TestNetworkContext {
     void SendMessage(network::mojom::WebSocketMessageType type,
                      uint64_t length) override {
       if (!peer_ || !peer_->connected_) {
-        pending_messages_.emplace_back(std::make_tuple(type, length));
+        pending_messages_.emplace_back(std::make_pair(type, length));
       } else {
         peer_->client_receiver_->OnDataFrame(/*final=*/true, type, length);
       }