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/y2019/vision/debug_serial.cc b/y2019/vision/debug_serial.cc
index c707d1f..18670c0 100644
--- a/y2019/vision/debug_serial.cc
+++ b/y2019/vision/debug_serial.cc
@@ -25,7 +25,7 @@
   // gflags::ParseCommandLineFlags(&argc, &argv, false);
   ::aos::logging::Init();
   ::aos::logging::SetImplementation(
-      new ::aos::logging::StreamLogImplementation(stderr));
+      std::make_shared<::aos::logging::StreamLogImplementation>(stderr));
 
   int flags = fcntl(0, F_GETFL, 0);
   fcntl(0, F_SETFL, flags | O_NONBLOCK);