[glom] Make some methods const.

[Murray Cumming <murrayc src gnome org>]

commit 41dece5cdbb44dfad95cdb7b4d6e98ca79f1b431
Author: Murray Cumming <murrayc murrayc com>
Date:   Tue Nov 3 17:44:08 2015 +0100

    Make some methods const.

 glom/import_csv/csv_parser.cc |    4 ++--
 glom/import_csv/csv_parser.h  |    4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/glom/import_csv/csv_parser.cc b/glom/import_csv/csv_parser.cc
index 71bfb51..77c12e5 100644
--- a/glom/import_csv/csv_parser.cc
+++ b/glom/import_csv/csv_parser.cc
@@ -100,7 +100,7 @@ bool CsvParser::get_rows_empty() const
   return m_rows.empty();
 }
 
-const Glib::ustring& CsvParser::get_data(guint row, guint col)
+const Glib::ustring& CsvParser::get_data(guint row, guint col) const
 {
   static Glib::ustring empty_result;
 
@@ -552,7 +552,7 @@ void CsvParser::on_buffer_read(const Glib::RefPtr<Gio::AsyncResult>& result)
   }
 }
 
-void CsvParser::on_file_query_info(const Glib::RefPtr<Gio::AsyncResult>& result, const 
Glib::RefPtr<Gio::File>& source)
+void CsvParser::on_file_query_info(const Glib::RefPtr<Gio::AsyncResult>& result, const 
Glib::RefPtr<Gio::File>& source) const
 {
   try
   {
diff --git a/glom/import_csv/csv_parser.h b/glom/import_csv/csv_parser.h
index c1f6cfe..41f5141 100644
--- a/glom/import_csv/csv_parser.h
+++ b/glom/import_csv/csv_parser.h
@@ -76,7 +76,7 @@ public:
   bool get_rows_empty() const;
 
   // The nasty reference return is for performance.
-  const Glib::ustring& get_data(guint row, guint col);
+  const Glib::ustring& get_data(guint row, guint col) const;
 
   /**  Fetches the next row from the parser's cache. It will block until enough
     *  data was parsed to return a row. An empty row indicates the last row was
@@ -174,7 +174,7 @@ private:
   void on_file_read(const Glib::RefPtr<Gio::AsyncResult>& result, const Glib::RefPtr<Gio::File>& source);
   void copy_buffer_and_continue_reading(gssize size);
   void on_buffer_read(const Glib::RefPtr<Gio::AsyncResult>& result);
-  void on_file_query_info(const Glib::RefPtr<Gio::AsyncResult>& result, const Glib::RefPtr<Gio::File>& 
source);
+  void on_file_query_info(const Glib::RefPtr<Gio::AsyncResult>& result, const Glib::RefPtr<Gio::File>& 
source) const;
 
   void set_state(State state);