As of golang.org/cl/9154, running go test will override a previous
go install -a -tags=lldb std with the tag-less version of stdlib. So
we pass -tags=lldb into the relevant go test commands.

Change-Id: I1c718289d7212373a9383eff53a643f06598f5ed
Reviewed-on: https://go-review.googlesource.com/10701Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>