[libsigcplusplus] signal_emit: Remove some public type aliases.

[Murray Cumming <murrayc src gnome org>]

commit 7502a6aa6df96a54b034b5722138f35e5aba1116
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Apr 21 19:23:40 2016 +0200

    signal_emit: Remove some public type aliases.

 sigc++/signal.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/sigc++/signal.h b/sigc++/signal.h
index 5198405..2958adf 100644
--- a/sigc++/signal.h
+++ b/sigc++/signal.h
@@ -233,8 +233,6 @@ struct signal_emit
 {
   using self_type = signal_emit<T_return, T_accumulator, T_arg...>;
   using slot_type = slot<T_return(T_arg...)>;
-  using slot_iterator_buf_type = internal::slot_iterator_buf<self_type, T_return>;
-  using iterator_type = signal_impl::const_iterator_type;
 
   /** Instantiates the class.
    * The parameters are stored in member variables. operator()() passes
@@ -259,6 +257,8 @@ struct signal_emit
    */
   static decltype(auto) emit(signal_impl* impl, type_trait_take_t<T_arg>... a)
   {
+    using slot_iterator_buf_type = internal::slot_iterator_buf<self_type, T_return>;
+
     T_accumulator accumulator;
 
     if (!impl)