Commands: remove `signalled` cases for Windows
Commands: remove `signalled` cases for Windows

Windows does not have the concept of signals, therefore processes may
not terminate with signalling exits.  Such an exit is encoded in the
exit status code on Windows.

abertelrud/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager,apple/swift-package-manager,apple/swift-package-manager,abertelrud/swift-package-manager