[libsigcplusplus] Use {} with multiline for() blocks.

[Murray Cumming <murrayc src gnome org>]

commit 2ec63aa8975ea9002fb7b85e1298a00b35089429
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Mar 31 15:24:59 2016 +0200

    Use {} with multiline for() blocks.

 sigc++/signal.h     |    4 ++++
 sigc++/trackable.cc |    4 ++++
 2 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/sigc++/signal.h b/sigc++/signal.h
index f880ddf..f1b2945 100644
--- a/sigc++/signal.h
+++ b/sigc++/signal.h
@@ -680,8 +680,10 @@ struct signal_emit<T_return, void, T_arg...>
       temp_slot_list slots(impl->slots_);
       iterator_type it = slots.begin();
       for (; it != slots.end(); ++it)
+      {
         if (!it->empty() && !it->blocked())
           break;
+      }
 
       if (it == slots.end())
       {
@@ -723,8 +725,10 @@ struct signal_emit<T_return, void, T_arg...>
       temp_slot_list slots(impl->slots_);
       reverse_iterator_type it(slots.end());
       for (; it != reverse_iterator_type(slots.begin()); ++it)
+      {
         if (!it->empty() && !it->blocked())
           break;
+      }
 
       if (it == reverse_iterator_type(slots.begin()))
       {
diff --git a/sigc++/trackable.cc b/sigc++/trackable.cc
index e74133a..d2a8990 100644
--- a/sigc++/trackable.cc
+++ b/sigc++/trackable.cc
@@ -106,8 +106,10 @@ trackable_callback_list::~trackable_callback_list()
   clearing_ = true;
 
   for (auto& callback : callbacks_)
+  {
     if (callback.func_)
       callback.func_(callback.data_);
+  }
 }
 
 void
@@ -127,8 +129,10 @@ trackable_callback_list::clear()
   clearing_ = true;
 
   for (auto& callback : callbacks_)
+  {
     if (callback.func_)
       callback.func_(callback.data_);
+  }
 
   callbacks_.clear();