TSCTestSupport: remove `PseudoTerminal` on Windows temporarily (#112)
TSCTestSupport: remove `PseudoTerminal` on Windows temporarily (#112)

While swift-package-manager is being brought up on Windows, we do not
have the tests running.  Windows does not have the `pty` concept nor the
supporting APIs.  For now disable the class to allow
swift-tools-support-core to build on Windows with swift-package-manager
which is required to bootstrap swift-package-manager.
apple/swift-tools-support-core,apple/swift-tools-support-core,apple/swift-tools-support-core,apple/swift-tools-support-core