go.tools/go/types: fix build (gc export format changed)
go.tools/go/types: fix build (gc export format changed)

Revision f280b8a485fd of the std library changed the
gc export format: anonymous fields may be qualified
with a package.

R=rsc
TBR=rsc
CC=golang-dev
https://codereview.appspot.com/14312043

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