runtime: add tests from Go 1.8

Some runtime package tests never made it into the gofrontend repo for
some reason.  Add them now.
Change-Id: I9a8b84a4035235929055e814bd73ad490f55516b
Reviewed-on: https://go-review.googlesource.com/40869
Reviewed-by: Than McIntosh <thanm@google.com>
5 files changed