os: add handling of os.Interrupt for windows
Add GenerateConsoleCtrlEvent call to internal syscall package.
Define ErrProcessDone while reviewing handling of os.Signal().
Update test to run for windows using the added call.
Fixes #42311
Fixes #46354
Change-Id: I460955efc76c4febe04b612ac9a0670e62ba5ff3
Reviewed-on: https://go-review.googlesource.com/c/go/+/367495
Trust: Patrik Nyblom <pnyb@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>