go.tools/go/types: mark imported named types as 'complete'
go.tools/go/types: mark imported named types as 'complete'

Fixes "illegal cycle" error for: go tool vet -v pkg/unicode.

R=adonovan
CC=golang-dev
https://codereview.appspot.com/12355043

t-yuki/go.tools.old,t-yuki/go.tools.old,tmc/mirror-go.tools,t-yuki/go.tools.old,tmc/mirror-go.tools,tmc/mirror-go.tools