Fixed compilation on Linux.

xs/src/slic3r/GUI/GUI.cpp

@@ -4,7 +4,6 @@
 #include <assert.h>
 #include <cmath>
 
-#include <boost/filesystem.hpp>
 #include <boost/lexical_cast.hpp>
 #include <boost/algorithm/string/split.hpp>
 #include <boost/algorithm/string/classification.hpp>

xs/src/slic3r/Utils/Serial.cpp

@@ -3,6 +3,7 @@
 #include <algorithm>
 
 #include <boost/algorithm/string/predicate.hpp>
+#include <boost/filesystem.hpp>
 
 #if _WIN32
 	#include <Windows.h>