x/tools/cmd/guru: remove unused method.
x/tools/cmd/guru: remove unused method.

Found with honnef.co/go/tools/cmd/unused.

Change-Id: Ied3a906269ca7782071428eeb1764b3b863576a2
Reviewed-on: https://go-review.googlesource.com/37600
Reviewed-by: Alan Donovan <7069e9552f9d110b0a0f326b96f22f63fb99dfc1@google.com>

syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools,golang/tools,syreclabs/go-tools,syreclabs/go-tools,syreclabs/go-tools,golang/tools,golang/tools,golang/tools,golang/tools