runtime: "found pointer to free object" on solaris-amd64-oraclerel

[bcmills]

2021-03-04T21:47:26-9d3718e/solaris-amd64-oraclerel
2021-02-24T16:38:32-ae1fa08/solaris-amd64-oraclerel
2020-11-21T16:46:05-9ea6364/solaris-amd64-oraclerel
2020-10-19T21:40:56-70cad27/solaris-amd64-oraclerel

I haven't been watching solaris-amd64-oraclerel very closely because it's fairly flaky, but this came to my attention via #44900.

[bcmills]

Note that the most recent of these failures occurred after #44614 was fixed.

[prattmic]

2021-04-28T02:39:09-92d1afe/solaris-amd64-oraclerel
2021-04-20T16:44:18-109d758/solaris-amd64-oraclerel
2021-03-25T19:20:52-ffa9983/solaris-amd64-oraclerel

[bcmills]

greplogs --dashboard -md -l -e '(?ms)\Asolaris-amd64-oraclerel.*found pointer to free object' --since=2021-04-29

2021-11-05T21:26:54-3e9e024/solaris-amd64-oraclerel
2021-10-19T22:47:35-9fa8551/solaris-amd64-oraclerel
2021-09-22T23:17:55-ee69b09/solaris-amd64-oraclerel
2021-08-23T15:27:42-f1d8ea1/solaris-amd64-oraclerel
2021-08-16T14:27:31-fe489c8/solaris-amd64-oraclerel
2021-06-21T14:58:02-7a5e704/solaris-amd64-oraclerel