[glibmm] connection_add_exception_handler(): Use list<slot> instead of signal.

[Murray Cumming <murrayc src gnome org>]

commit 59db6a2dcf7344ad2a21927535c2cd9a865267cd
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Apr 22 09:51:22 2016 +0200

    connection_add_exception_handler(): Use list<slot> instead of signal.
    
    Because libsigc++ 2.10 deprecates signal::slots() and libsigc++ 3.0
    now has no signal<>::slots() method. Using a signal for the list of
    slots seems rather non-obvious anyway.

 glib/glibmm/exceptionhandler.cc |   13 +++++++------
 1 files changed, 7 insertions(+), 6 deletions(-)
---
diff --git a/glib/glibmm/exceptionhandler.cc b/glib/glibmm/exceptionhandler.cc
index 31ddb39..95032a3 100644
--- a/glib/glibmm/exceptionhandler.cc
+++ b/glib/glibmm/exceptionhandler.cc
@@ -32,7 +32,7 @@
 namespace
 {
 
-using HandlerList = sigc::signal<void>;
+using HandlerList = std::list<sigc::slot<void()>>;
 
 // Each thread has its own list of exception handlers
 // to avoid thread synchronization problems.
@@ -108,8 +108,9 @@ add_exception_handler(const sigc::slot<void>& slot)
 #endif
   }
 
-  handler_list->slots().push_front(slot);
-  return handler_list->slots().begin();
+  handler_list->emplace_back(slot);
+  auto& added_slot = handler_list->back();
+  return sigc::connection(added_slot);
 }
 
 // internal
@@ -135,15 +136,15 @@ exception_handlers_invoke() noexcept
   if(HandlerList *const handler_list = thread_specific_handler_list.get())
 #endif
   {
-    HandlerList::iterator pslot = handler_list->slots().begin();
+    HandlerList::iterator pslot = handler_list->begin();
 
-    while (pslot != handler_list->slots().end())
+    while (pslot != handler_list->end())
     {
       // Calling an empty slot would mean ignoring the exception,
       // thus we have to check for dead slots explicitly.
       if (pslot->empty())
       {
-        pslot = handler_list->slots().erase(pslot);
+        pslot = handler_list->erase(pslot);
         continue;
       }