cmd/go: add -args to 'go test' to resolve -v ambiguity
The new flag -args stops flag processing, leaving the rest of the command line
to be passed to the underlying test binary verbatim. Thus, both of these pass
a literal -v -n on the test binary command line, without putting the go command
into verbose mode or disabling execution of commands:
go test . -args -v -n
go test -args -v -n
Also try to make the documentation a bit clearer.
Fixes #7221.
Fixes #12177.
Change-Id: Ief9e830a6fbb9475d96011716a86e2524a35eceb
Reviewed-on: https://go-review.googlesource.com/17775 Reviewed-by: Rob Pike <r@golang.org>