gotest: avoid conflicts with the name of the tested package
gotest: avoid conflicts with the name of the tested package

Uses a generic solution of renaming the tested package, instead of
using cryptic names for all other imports, variables and methods
in the generated _testmain.go file.

Fixes issue 2346.

R=golang-dev, r, adg
CC=golang-dev, rsc
http://codereview.appspot.com/5254061

Committer: Andrew Gerrand <395a7d33bec8475c9b83b7d440f141bcbd994aa5@golang.org>

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang