/usr/include/buteosyncfw5/ is in libbuteosyncfw5-dev 0.7.21+16.04.20151216.1-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/buteosyncfw5/BtHelper.h
/usr/include/buteosyncfw5/ButeoPluginIface.h
/usr/include/buteosyncfw5/ButeoPluginIfaceAdaptor.cpp
/usr/include/buteosyncfw5/ButeoPluginIfaceAdaptor.h
/usr/include/buteosyncfw5/ClientPlugin.h
/usr/include/buteosyncfw5/DeletedItemsIdStorage.h
/usr/include/buteosyncfw5/LogMacros.h
/usr/include/buteosyncfw5/Logger.h
/usr/include/buteosyncfw5/NetworkManager.h
/usr/include/buteosyncfw5/PluginCbImpl.cpp
/usr/include/buteosyncfw5/PluginCbImpl.h
/usr/include/buteosyncfw5/PluginCbInterface.h
/usr/include/buteosyncfw5/PluginManager.h
/usr/include/buteosyncfw5/PluginServiceObj.cpp
/usr/include/buteosyncfw5/PluginServiceObj.h
/usr/include/buteosyncfw5/Profile.h
/usr/include/buteosyncfw5/ProfileEngineDefs.h
/usr/include/buteosyncfw5/ProfileFactory.h
/usr/include/buteosyncfw5/ProfileField.h
/usr/include/buteosyncfw5/ProfileManager.h
/usr/include/buteosyncfw5/Profile_p.h
/usr/include/buteosyncfw5/ServerPlugin.h
/usr/include/buteosyncfw5/StorageChangeNotifierPlugin.h
/usr/include/buteosyncfw5/StorageItem.h
/usr/include/buteosyncfw5/StoragePlugin.h
/usr/include/buteosyncfw5/StorageProfile.h
/usr/include/buteosyncfw5/SyncClientInterface.h
/usr/include/buteosyncfw5/SyncClientInterfacePrivate.h
/usr/include/buteosyncfw5/SyncCommonDefs.h
/usr/include/buteosyncfw5/SyncDaemonProxy.h
/usr/include/buteosyncfw5/SyncLog.h
/usr/include/buteosyncfw5/SyncPluginBase.h
/usr/include/buteosyncfw5/SyncProfile.h
/usr/include/buteosyncfw5/SyncResults.h
/usr/include/buteosyncfw5/SyncSchedule.h
/usr/include/buteosyncfw5/SyncSchedule_p.h
/usr/include/buteosyncfw5/TargetResults.h
/usr/include/buteosyncfw5/TransportTracker.h
/usr/include/buteosyncfw5/plugin_main.cpp