runtime: TestCgoExternalThreadPanic failures with `exit status 2`

[bcmills]

#!watchflakes
post <- pkg == "runtime" && test == "TestCgoExternalThreadPanic" && `exit status 2`

Factored out from #57381 (comment).

(attn @golang/mips; CC @golang/runtime)

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
post <- pkg == "runtime" && test == "TestCgoExternalThreadPanic" && `exit status 2`

2023-01-18 19:33 linux-mips64-rtrk go@6fcbd036 runtime.TestCgoExternalThreadPanic (log)

--- FAIL: TestCgoExternalThreadPanic (49.62s)
    crash_test.go:58: /tmp/gobuilder-mips64/tmp/go-build3897220462/testprogcgo.exe CgoExternalThreadPanic: exit status 2
    crash_cgo_test.go:86: want failure containing "panic: BOOM". output:

2023-01-24 01:02 linux-mips64-rtrk go@7135710e runtime.TestCgoExternalThreadPanic (log)

--- FAIL: TestCgoExternalThreadPanic (63.59s)
    crash_test.go:58: /tmp/gobuilder-mips64/tmp/go-build3992749568/testprogcgo.exe CgoExternalThreadPanic: exit status 2
    crash_cgo_test.go:86: want failure containing "panic: BOOM". output:

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
post <- pkg == "runtime" && test == "TestCgoExternalThreadPanic" && `exit status 2`

2023-05-24 03:36 linux-s390x-ibm go@f0d575c2 runtime.TestCgoExternalThreadPanic (log)

--- FAIL: TestCgoExternalThreadPanic (0.08s)
    exec.go:190: test timed out while running command: /data/golang/workdir/tmp/go-build4029398001/testprogcgo.exe CgoExternalThreadPanic
    crash_cgo_test.go:84: /data/golang/workdir/tmp/go-build4029398001/testprogcgo.exe CgoExternalThreadPanic: exit status 2

— watchflakes

[gopherbot]

Found new dashboard test flakes for:

#!watchflakes
post <- pkg == "runtime" && test == "TestCgoExternalThreadPanic" && `exit status 2`

2023-07-27 22:07 linux-s390x-ibm go@3bc28402 runtime.TestCgoExternalThreadPanic (log)

--- FAIL: TestCgoExternalThreadPanic (0.48s)
    crash_cgo_test.go:84: /data/golang/workdir/tmp/go-build2885226197/testprogcgo.exe CgoExternalThreadPanic: exit status 2
    crash_cgo_test.go:87: want failure containing "panic: BOOM". output:

— watchflakes