Update git submodules

* Update ChronoSync from branch 'master'
  - Update doxygen configuration
    
    Change-Id: Ibd39a0567284901ef2c8c6dc53ab76661c711868
    
  - Use ndn::Buffer::data() instead of buf()
    
    The latter is considered deprecated.
    
    Change-Id: If92406ccedca391e3551b456491ebb47737f1bc1
    
diff --git a/ChronoSync b/ChronoSync
index 12d5faa..f93a145 160000
--- a/ChronoSync
+++ b/ChronoSync
@@ -1 +1 @@
-Subproject commit 12d5faa1f8820afbd493b45d69310013973d6440
+Subproject commit f93a14591de4e196a99c3be5064bb2740d03e79e