Pl_editor: fix a incorrect include:

The included file was a .cpp file instead of the corresponding .h file

pagelayout_editor/CMakeLists.txt

@@ -21,6 +21,7 @@ set( PL_EDITOR_SRCS
     pl_editor_layout.cpp
     files.cpp
     pl_editor_frame.cpp
+    pl_draw_panel_gal.cpp
     pl_editor_undo_redo.cpp
     properties_frame.cpp
     hotkeys.cpp

pagelayout_editor/pl_editor_frame.cpp

@@ -32,7 +32,7 @@
 #include <eda_dockart.h>
 #include <pl_editor_frame.h>
 #include <pl_editor_id.h>
-#include <pl_draw_panel_gal.cpp>
+#include <pl_draw_panel_gal.h>
 #include <hotkeys.h>
 #include <pl_editor_screen.h>
 #include <ws_data_model.h>