Fixes compile error with SLIC3R_PCH=OFF (#9543)

fixes compile error with SLIC3R_PCH=OFF

flatpak/io.github.softfever.OrcaSlicer.yml

@@ -298,7 +298,7 @@ modules:
       - |
         mkdir -p build
         CXXFLAGS=-std=gnu++20 cmake . -B build \
-          -DSLIC3R_PCH=ON \
+          -DSLIC3R_PCH=OFF \
           -DSLIC3R_FHS=ON \
           -DSLIC3R_GTK=3 \
           -DSLIC3R_STATIC=ON \

src/slic3r/GUI/2DBed.hpp

@@ -3,6 +3,8 @@
 
 #include <wx/wx.h>
 #include "libslic3r/Config.hpp"
+#include "libslic3r/ExPolygon.hpp"
+#include "libslic3r/Polyline.hpp"
 
 namespace Slic3r {
 namespace GUI {