runtime: frequent SIGSEGV in readgstatus in bootstrap toolchain

[cherrymui]

Spilt off from #49686 to be clear about the current issue with the bootstrap toolchain and not to be confused with the old bug.

The original bug in #49686 has been fixed in Go 1.18. We are currently using Go 1.17 as the bootstrap toolchain which doesn't contain the fix, and we still occasionally see the failure.

It seems the current decision is to wait and see if more failures come up and see whether it is the bootstrap toolchain's issue. Then we can make a decision, e.g. backporting the fix, or bumping the bootstrap version.

cc @mknyszek @rsc @bcmills

[gopherbot]

Timed out in state WaitingForInfo. Closing.

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