more missing includes (SoftFever#5930)

Here are more missing header files recently identified by building
without precompiled header support.

src/libslic3r/GCode/SmallAreaInfillFlowCompensator.cpp

@@ -9,6 +9,7 @@
 #include <math.h>
 #include <cstring>
 #include <cfloat>
+#include <regex>
 
 #include "../libslic3r.h"
 #include "../PrintConfig.hpp"

src/libslic3r/Interlocking/VoxelUtils.cpp

@@ -4,6 +4,7 @@
 #include "VoxelUtils.hpp"
 #include "../Geometry.hpp"
 #include "../Fill/FillRectilinear.hpp"
+#include "../Surface.hpp"
 
 namespace Slic3r
 {

src/libslic3r/Interlocking/VoxelUtils.hpp

@@ -7,6 +7,7 @@
 #include <functional>
 
 #include "../Polygon.hpp"
+#include "../ExPolygon.hpp"
 
 namespace Slic3r
 {

src/libslic3r/PerimeterGenerator.cpp

@@ -18,6 +18,7 @@
 #include <cassert>
 #include <random>
 #include <unordered_set>
+#include <thread>
 #include "libslic3r/AABBTreeLines.hpp"
 static const int overhang_sampling_number = 6;
 static const double narrow_loop_length_threshold = 10;

src/slic3r/Utils/Http.hpp

@@ -6,6 +6,7 @@
 #include <string>
 #include <functional>
 #include <boost/filesystem/path.hpp>
+#include <boost/filesystem/fstream.hpp>
 
 #include "libslic3r/Exception.hpp"
 #include "libslic3r_version.h"