Fix missing includes

Likey due to
https://github.com/openbmc/sdbusplus/commit/38ab5ecfe3c51501a9380e2c30dbb5fdd88cf4f9

Some Boost features that were missing from being included
made the build stop working. Fix them.

Change-Id: If1c1d08961f5c2fb7512ddc3cea65a97aa2a9e2b
Signed-off-by: Jason M. Bills <jason.m.bills@intel.com>
diff --git a/src/host_error_monitor.cpp b/src/host_error_monitor.cpp
index 313ef29..c637188 100644
--- a/src/host_error_monitor.cpp
+++ b/src/host_error_monitor.cpp
@@ -16,7 +16,9 @@
 #include <peci.h>
 #include <systemd/sd-journal.h>
 
+#include <boost/asio/io_service.hpp>
 #include <boost/asio/posix/stream_descriptor.hpp>
+#include <boost/asio/steady_timer.hpp>
 #include <gpiod.hpp>
 #include <sdbusplus/asio/object_server.hpp>