main: drop unused headers

Drop unused headers from main.cpp:
 - experimental/any
 - mutex

Change-Id: I1bd0180e8582bc9c80e67bbb5e3bb5d040c218cc
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/main.cpp b/main.cpp
index 3ed84f6..8e781bc 100644
--- a/main.cpp
+++ b/main.cpp
@@ -31,11 +31,9 @@
 #include <getopt.h>
 
 #include <chrono>
-#include <experimental/any>
 #include <iostream>
 #include <map>
 #include <memory>
-#include <mutex> /* not yet used. */
 #include <sdbusplus/bus.hpp>
 #include <thread>
 #include <unordered_map>