undo CL 12787044 / ed695cdf962b

The NetBSD and OpenBSD failures are apparently real,
not due to the test bug fixed in 100b9fc0c46f.

??? original CL description
runtime/pprof: test netbsd and openbsd again

Maybe these will work now.

R=golang-dev, dvyukov, bradfitz
CC=golang-dev
https://codereview.appspot.com/12787044
???

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12873043

Committer: Dmitriy Vyukov <dvyukov@google.com>
runtime: tell GC not to scan internal hashmap structures.
We'll do it ourselves via hash_gciter, thanks.
Fixes bug 6119.

R=golang-dev, dvyukov, cookieo9, rsc
CC=golang-dev
https://codereview.appspot.com/12840043