runtime/pprof: frequent test timeouts on builders since mid-August

[bcmills]

2020-08-22T03:46:17-13e41bc/android-386-emu
2020-08-19T03:49:06-bd519d0/android-386-emu

Also https://storage.googleapis.com/go-build-log/1be3e58d/openbsd-amd64-64_e5acea9b.log.

CC @hyangah

[bcmills]

2020-08-24T20:22:16-5c76382/linux-386-sid

Given the rash of failures in August, this is looking like a 1.16 regression, so marking as release-blocker.

[bcmills]

Turns out my regexp had missed some. 😅

Still looks to me like there may be an inflection point in August, though.

2020-08-24T20:25:55-9bcc5d2/openbsd-386-62
2020-08-24T20:22:16-5c76382/linux-386-sid
2020-08-24T16:41:53-494ec85/linux-arm
2020-08-24T13:59:40-0e03167/openbsd-amd64-62
2020-08-23T05:24:15-0c3bf27/solaris-amd64-oraclerel
2020-08-22T03:46:17-13e41bc/android-386-emu
2020-08-21T21:53:38-e5da468/solaris-amd64-oraclerel
2020-08-19T22:26:47-b0cc02e/solaris-amd64-oraclerel
2020-08-19T14:44:18-8d91d73/linux-arm
2020-08-19T03:49:06-bd519d0/android-386-emu
2020-08-17T19:45:42-797124f/linux-arm
2020-05-14T16:20:19-796786c/linux-mips64-rtrk
2019-11-26T12:03:08-20bf6a4/linux-mips64le-rtrk
2019-11-24T15:06:38-b81dd1c/windows-amd64-race
2019-11-04T23:41:34-383b447/android-amd64-emu
2019-10-08T06:09:26-77f5adb/darwin-arm-mg912baios
2019-10-05T22:17:49-80fb18e/darwin-arm-mg912baios

[bcmills]

https://storage.googleapis.com/go-build-log/8921b4e8/android-amd64-emu_69e10eb0.log (a TryBot run)

@golang/osp-team, could we bisect and revert the CL that introduced this apparent regression?

[bcmills]

2020-08-31T18:42:38-e01a226/freebsd-amd64-11_2
2020-08-29T09:20:35-4fc3896/linux-amd64-clang
2020-08-27T23:25:58-42fd130/linux-amd64-staticlockranking
2020-08-27T23:25:58-42fd130/netbsd-386-9_0
2020-08-27T23:19:15-4f76fe8/linux-386-longtest
2020-08-27T22:35:45-8247da3/linux-386
2020-08-27T19:38:43-a98fe26/solaris-amd64-oraclerel
2020-08-27T18:28:53-c00b708/android-arm64-corellium
2020-08-27T17:57:10-3b20d48/linux-amd64-staticlockranking
2020-08-26T21:17:01-eb3e27a/android-amd64-emu
2020-08-26T21:17:01-eb3e27a/freebsd-386-11_2
2020-08-25T17:37:38-5e1e8c4/freebsd-amd64-12_0
2020-08-25T17:34:17-91a52de/linux-arm64-packet
2020-08-25T14:51:49-bca0b44/android-arm64-corellium
2020-08-24T21:08:46-95df156/linux-amd64

[bcmills]

https://storage.googleapis.com/go-build-log/39e65426/linux-amd64-race_d8c01c0c.log (another TryBot)