windows-amd64 tests flaky (cgo and others)

https://dev.azure.com/dnceng/internal/_build/results?buildId=1450673&view=results hit:

=== Failed
=== FAIL: runtime TestSyscallN/arg-6 (unknown)
=== FAIL: runtime TestSyscallN/arg-1 (unknown)
=== FAIL: runtime TestSyscallN/arg-13 (unknown)
=== FAIL: runtime TestCgoPprofThreadNoTraceback (unknown)
=== FAIL: runtime TestVDSO (unknown)
=== FAIL: runtime TestCgoExternalThreadSignal (unknown)
=== FAIL: runtime TestCgoCrashHandler (unknown)
=== FAIL: runtime TestSyscallN/arg-12 (unknown)
=== FAIL: runtime TestSyscallN/arg-7 (unknown)
=== FAIL: runtime TestSyscallN/arg-22 (unknown)
=== FAIL: runtime TestSyscallN/arg-0 (unknown)
=== FAIL: runtime TestSyscallN/arg-16 (unknown)
=== FAIL: runtime TestCgoPprofPIE (unknown)
=== FAIL: runtime TestNetpollDeadlock (unknown)
=== FAIL: runtime TestConcurrentReadsAfterGrowthReflect (unknown)
=== FAIL: runtime TestSyscallN/arg-11 (unknown)
=== FAIL: runtime TestCgoExecSignalMask (unknown)
=== FAIL: runtime TestCgoCheckBytes (unknown)
=== FAIL: runtime TestCgoTracebackContext (unknown)
=== FAIL: runtime TestCgoCallbackGC (unknown)
=== FAIL: runtime TestCgoPanicDeadlock (unknown)
=== FAIL: runtime TestRecoverBeforePanicAfterGoexit2 (unknown)
=== FAIL: runtime TestEnsureDropM (unknown)
=== FAIL: runtime TestBigGOMAXPROCS (unknown)
=== FAIL: runtime TestSyscallN/arg-20 (unknown)
=== FAIL: runtime TestCgoCCodeSIGPROF (unknown)
=== FAIL: runtime TestPanicTraceback (unknown)
=== FAIL: runtime TestCheckPtr (unknown)

Not all are clearly related to cgo, but there are a decent number in there. Potentially related:

• https://github.com/golang/go/issues/49188

Start with the linked Azure build results and reproduce the failures in the windows-amd64 runtime tests, including TestSyscallN and the listed cgo tests. Compare the failures with the related issue #49188; done means identifying the cause and making the affected tests reliable.