Enable and fix chromium clang warnings in rtp_rtcp test targets

Bug: webrtc:163
Change-Id: I4ed3e63296d8bf06536a83196d597c7a906ba11c
Reviewed-on: https://webrtc-review.googlesource.com/60802
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22357}

modules/rtp_rtcp/source/byte_io_unittest.cc

@@ -18,8 +18,8 @@ namespace {
 
 class ByteIoTest : public ::testing::Test {
  protected:
-  ByteIoTest() {}
-  virtual ~ByteIoTest() {}
+  ByteIoTest() = default;
+  ~ByteIoTest() override = default;
 
   enum { kAlignments = sizeof(uint64_t) - 1 };