Tracing: add explicit dtor to TracingMuxerFake

Some SDK users hit linking errors when building perfetto.cc
The cause is uknown (esepcially given they were building the
same perfetto.cc in 3 targets with the same compiler and only
one failed).

The linking error was:
'perfetto::internal::TracingMuxerFake::~TracingMuxerFake()'
buck-out/gen/arvr/third-party/perfetto/perfetto_sdk#android-arm64,static/libperfetto_sdk.a(out.o):perfetto.cc:vtable for perfetto::internal::TracingMuxerFake: error: undefined reference to 'perfetto::internal::TracingMuxerFake::~TracingMuxerFake()'
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

Change-Id: I20d3889470777edc18c0871271b735a522e3708b
Bug: discord chat of 2021-07-20
diff --git a/CHANGELOG b/CHANGELOG
index e233933..d8109b4 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,12 +2,12 @@
   Tracing service and probes:
     *
   Trace Processor:
-    * Removed the RawQuery RPC interface. 
+    * Removed the RawQuery RPC interface.
   UI:
-    * Added a highlighted section to thread slices to visualize CPU time 
+    * Added a highlighted section to thread slices to visualize CPU time
       (darker) verses wall time (lighter).
   SDK:
-    *
+    * Fix undefined reference on ~TracingMuxerFake when building the SDK.
 
 
 v17.0 - 2021-07-02: