Change includes in Spreadsheet to be compatible with Qt5.

This change is Qt4/Qt5 neutral.

src/Mod/Spreadsheet/Gui/AppSpreadsheetGui.cpp

@@ -22,7 +22,12 @@
 #include "Workbench.h"
 #include "ViewProviderSpreadsheet.h"
 #include "SpreadsheetView.h"
+
+#if QT_VERSION >= 0x050000
+#include "qrc_Spreadsheet.cpp"
+#else
 #include "qrc_Spreadsheet.cxx"
+#endif
 
 // use a different name to CreateCommand()
 void CreateSpreadsheetCommands(void);