Add missing include for boost::flat_map

A recent update to sdbusplus exposed a missing include. This adds the
include to fix the build.

Signed-off-by: Jason M. Bills <jason.m.bills@intel.com>
Change-Id: I7db08ff8c85fa2dcf234ff42956b68c6ca6eb0e4
diff --git a/src/cpuinfo_main.cpp b/src/cpuinfo_main.cpp
index 4633174..8d8cce5 100644
--- a/src/cpuinfo_main.cpp
+++ b/src/cpuinfo_main.cpp
@@ -25,6 +25,7 @@
 
 #include <boost/asio/io_service.hpp>
 #include <boost/asio/steady_timer.hpp>
+#include <boost/container/flat_map.hpp>
 
 #include <iostream>
 #include <list>