[libsigcplusplus] Fixed missing newline in doxygen comment.

[Murray Cumming <murrayc src gnome org>]

commit d8c2dff2fd0c45252bbbd3a85463f45b504977d2
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Apr 21 19:32:07 2016 +0200

    Fixed missing newline in doxygen comment.

 sigc++/signal.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/sigc++/signal.h b/sigc++/signal.h
index c641f03..a0a45bf 100644
--- a/sigc++/signal.h
+++ b/sigc++/signal.h
@@ -302,8 +302,8 @@ public:
    * The arguments are passed directly on to the slots.
    * The return value of the last slot invoked is returned.
    * @param first An iterator pointing to the first slot in the list.
-   * @param last An iterator pointing to the last slot in the list.   * @param a Arguments to be
-   * passed on to the slots.
+   * @param last An iterator pointing to the last slot in the list.
+   * @param a Arguments to be passed on to the slots.
    * @return The return value of the last slot invoked.
    */
   static decltype(auto) emit(signal_impl* impl, type_trait_take_t<T_arg>... a)