Build: use piecemeal boost headers.

Reduces compile time on a 4-core ARM Rpi5 from 1m12s wallclock
(i.e: "real") time to 0m55s; and from 4m+ "user" time to 3m8s.

smocore/componentThread.cpp

@@ -2,7 +2,7 @@
 #include <iostream>
 #include <pthread.h>
 #include <sched.h>
-#include <boost/asio.hpp>
+#include <boost/asio/io_service.hpp>
 #include <opts.h>
 #include <asynchronousContinuation.h>
 #include <callback.h>

smocore/include/componentThread.h

@@ -4,7 +4,7 @@
 #include <atomic>
 #include <thread>
 #include <unordered_map>
-#include <boost/asio.hpp>
+#include <boost/asio/io_service.hpp>
 #include <stdexcept>
 #include <queue>
 #include <functional>

smocore/include/deviceManager/deviceReattacher.h

@@ -3,7 +3,8 @@
 
 #include <atomic>
 #include <memory>
-#include <boost/asio.hpp>
+#include <boost/asio/io_service.hpp>
+#include <boost/asio/deadline_timer.hpp>
 
 namespace smo {