Register pprof handlers for log_signer. (#1210)
Register pprof handlers for log_signer. (#1210)

These are already registered for map_server and log_server.
RJPercival/trillian,gdbelvin/trillian,daviddrysdale/trillian,Martin2112/trillian,google/trillian,Martin2112/trillian,AlCutter/trillian,daviddrysdale/trillian,RJPercival/trillian,Martin2112/trillian,gdbelvin/trillian,google/trillian,AlCutter/trillian,gdbelvin/trillian,daviddrysdale/trillian