runtime: frequent test timeouts on illumos-amd64 builder since March

[bcmills]

Most of these timeouts are in runTestProg, runBuildTestProg, and/or buildTestProg, so it may be that building and linking programs on this builder take longer than the runtime package expects. It's not clear to me whether this indicates a problem with the builder, an unrealistic assumption in the test, or something else entirely.

2021-05-30T02:37:38-1607c28/illumos-amd64
2021-05-26T16:11:00-bfd7798/illumos-amd64
2021-05-26T05:45:56-d050238/illumos-amd64
2021-05-20T16:09:29-ef1f52c/illumos-amd64
2021-05-14T16:42:01-3d324f1/illumos-amd64
2021-05-12T17:32:39-f93b951/illumos-amd64
2021-05-12T15:23:09-0388670/illumos-amd64
2021-05-12T15:04:42-af0f8c1/illumos-amd64
2021-05-09T17:07:01-bedf2c4/illumos-amd64
2021-05-08T14:59:49-68327e1/illumos-amd64
2021-05-08T05:57:31-4c8f48e/illumos-amd64
2021-05-07T17:43:31-b44c78b/illumos-amd64
2021-05-07T02:17:32-d2b0311/illumos-amd64
2021-05-06T15:33:43-54e20b5/illumos-amd64
2021-05-05T01:28:34-4df662f/illumos-amd64
2021-05-03T01:35:44-2c9f5a1/illumos-amd64
2021-05-02T20:38:13-fadad85/illumos-amd64
2021-04-30T19:38:25-d19eece/illumos-amd64
2021-04-30T18:46:51-afa58dd/illumos-amd64
2021-04-30T18:07:24-c3365ad/illumos-amd64
2021-04-29T19:04:31-87e4dcd/illumos-amd64
2021-04-29T14:06:55-d80da19/illumos-amd64
2021-04-28T20:36:50-fa6ed6e/illumos-amd64
2021-04-28T00:49:58-c9f4350/illumos-amd64
2021-04-23T21:43:04-79f3513/illumos-amd64
2021-04-23T21:42:57-c0e1301/illumos-amd64
2021-04-23T21:42:56-073f913/illumos-amd64
2021-04-22T22:01:47-7405968/illumos-amd64
2021-04-22T04:07:38-14a18b7/illumos-amd64
2021-04-22T00:34:25-02a8e83/illumos-amd64
2021-04-21T21:14:04-54af9fd/illumos-amd64
2021-04-20T20:14:14-7473a6a/illumos-amd64
2021-04-20T14:30:03-3ff6ff7/illumos-amd64
2021-04-16T21:03:51-800fb11/illumos-amd64
2021-04-15T12:38:11-dba2eab/illumos-amd64
2021-04-14T04:02:01-6d8ba77/illumos-amd64
2021-04-13T20:07:47-69262d4/illumos-amd64
2021-04-13T14:13:57-4b00eb7/illumos-amd64
2021-04-12T21:59:59-263e13d/illumos-amd64
2021-04-12T21:59:20-3d5e3a1/illumos-amd64
2021-04-08T02:17:23-8752454/illumos-amd64
2021-04-06T22:55:58-b084073/illumos-amd64
2021-04-02T21:59:37-2ebe77a/illumos-amd64
2021-04-02T20:26:12-35a8bbc/illumos-amd64
2021-04-02T19:45:52-41cf18e/illumos-amd64
2021-04-02T19:27:06-34b87b4/illumos-amd64
2021-04-02T16:53:18-28c5fed/illumos-amd64
2021-04-02T14:40:43-3651eff/illumos-amd64
2021-04-02T00:45:56-5579ee1/illumos-amd64
2021-03-25T04:14:58-ddcdbb4/illumos-amd64
2021-03-16T13:06:17-120b9eb/illumos-amd64
2021-03-14T21:10:45-3cdd5c3/illumos-amd64
2021-03-13T18:03:52-8336c31/illumos-amd64
2021-03-11T16:37:38-0fc370c/illumos-amd64
2021-03-11T08:19:31-79e3ee5/illumos-amd64
2021-03-09T22:00:50-142a765/illumos-amd64
2021-03-07T23:58:09-597b5d1/illumos-amd64
2021-03-07T23:02:35-b0df927/illumos-amd64
2021-03-05T17:46:57-67b9ecb/illumos-amd64

CC @golang/release

[bcmills]

I thought I had filed an issue for this but couldn't find it. Turns out I had previously filed #44422, initially for the linux-ppc64le-buildlet builder.

[bcmills]

It's curious, though, that the illumos-amd64 timeouts started in March, whereas the linux-ppc64le failures have been happening since long before.

[bcmills]

These failures don't seem to be builder-specific — the runtime test is just too slow on the short-testing builders.

[bcmills]

Duplicate of #44422.