ftbfs on gcc6

In file included from /«BUILDDIR»/dbus-cpp-5.0.0+15.10.20151022.1/include/core/dbus/signal.h:207:0,
                 from /«BUILDDIR»/dbus-cpp-5.0.0+15.10.20151022.1/include/core/dbus/dbus.h:22,
                 from /«BUILDDIR»/dbus-cpp-5.0.0+15.10.20151022.1/src/core/dbus/bus.cpp:20:
/«BUILDDIR»/dbus-cpp-5.0.0+15.10.20151022.1/include/core/dbus/impl/signal.h: In member function ‘void core::dbus::Signal<SignalDescription, Argument>::disconnect(const SubscriptionToken&)’:
/«BUILDDIR»/dbus-cpp-5.0.0+15.10.20151022.1/include/core/dbus/impl/signal.h:68:32: error: return-statement with a value, in function returning 'void' [-fpermissive]
     return handlers.erase(token);
                                ^
src/core/dbus/CMakeFiles/dbus-cpp.dir/build.make:89: recipe for target 'src/core/dbus/CMakeFiles/dbus-cpp.dir/bus.cpp.o' failed

from https://launchpadlibrarian.net/271608434/buildlog_ubuntu-yakkety-i386.dbus-cpp_5.0.0+15.10.20151022.1-0ubuntu3_BUILDING.txt.gz