Actually manage memory in the old-style AOS logging

LeakSanitizer should be happy with it now. It's also still just as
thread-safe.

Change-Id: Id09a0349657cf4f719267b053f0ea3d8ec366256
diff --git a/y2018/vision/image_streamer.cc b/y2018/vision/image_streamer.cc
index fa5f4b5..06a74c4 100644
--- a/y2018/vision/image_streamer.cc
+++ b/y2018/vision/image_streamer.cc
@@ -290,7 +290,7 @@
   gflags::ParseCommandLineFlags(&argc, &argv, false);
   ::aos::logging::Init();
   ::aos::logging::SetImplementation(
-      new ::aos::logging::StreamLogImplementation(stderr));
+      std::make_shared<::aos::logging::StreamLogImplementation>(stderr));
 
   TCPServer<MjpegDataSocket> tcp_server_(80);
   aos::vision::CameraParams params0;