go.tools/cmd/godoc: add redirects for godoc, vet, and gotest
go.tools/cmd/godoc: add redirects for godoc, vet, and gotest

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/13709046

bryanxu/go-zh.tools,skyportsystems/go.tools,webfd/go-zh.tools,bryanxu/go-zh.tools,bryanxu/go-zh.tools,skyportsystems/go.tools,webfd/go-zh.tools,webfd/go-zh.tools,webfd/go-zh.tools,8limbs/gotools,d0f/go-zh.tools,webfd/go-zh.tools,d0f/go-zh.tools,bryanxu/go-zh.tools,d0f/go-zh.tools,8limbs/gotools,d0f/go-zh.tools,skyportsystems/go.tools,skyportsystems/go.tools,bryanxu/go-zh.tools,d0f/go-zh.tools,8limbs/gotools,skyportsystems/go.tools