dbus: Disable FB303 autoregister if thrift isn't installed
dbus: Disable FB303 autoregister if thrift isn't installed

Allow dbus integration (e.g., for signal handling) even if thrift isn't available.

fmoo/sparts,djipko/sparts,facebook/sparts,facebook/sparts,bboozzoo/sparts,bboozzoo/sparts,djipko/sparts,fmoo/sparts