[glibmm] Gio::DataOutputStream::put_string(): Don't pass std:string by value

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 4089fba2b85e8fa5cc7039895399dbd179933ad4
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Thu Mar 1 15:23:58 2018 +0100

    Gio::DataOutputStream::put_string(): Don't pass std:string by value

 gio/src/dataoutputstream.hg |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gio/src/dataoutputstream.hg b/gio/src/dataoutputstream.hg
index 2e87789..aec65bf 100644
--- a/gio/src/dataoutputstream.hg
+++ b/gio/src/dataoutputstream.hg
@@ -61,7 +61,7 @@ public:
 
   _WRAP_METHOD(bool put_uint64(guint64 data, const Glib::RefPtr<Cancellable>& cancellable{?}), 
g_data_output_stream_put_uint64, errthrow)
 
-  _WRAP_METHOD(bool put_string(std::string str, const Glib::RefPtr<Cancellable>& cancellable{?}), 
g_data_output_stream_put_string, errthrow)
+  _WRAP_METHOD(bool put_string(const std::string& str, const Glib::RefPtr<Cancellable>& cancellable{?}), 
g_data_output_stream_put_string, errthrow)
 
   _WRAP_PROPERTY("byte-order", DataStreamByteOrder)
 };