[5.9.1] Enable macros for Windows in 5.9.1

[bnbarham]

Cherry-picks 6cbe5e0.

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Don't assume that the temporary directory doesn't include symlinks.

[bnbarham]

@swift-ci please test

[compnerd]

@swift-ci please test

[bnbarham]

@swift-ci please test macOS platform

[bnbarham]

Whole bunch of SwiftXCTestFunctionalTests failures on macOS:

Failed Tests (24):
  SwiftXCTestFunctionalTests :: ArgumentParser/main.swift
  SwiftXCTestFunctionalTests :: Asynchronous/Expectations/main.swift
  SwiftXCTestFunctionalTests :: Asynchronous/Handler/main.swift
  SwiftXCTestFunctionalTests :: Asynchronous/Misuse/main.swift
  SwiftXCTestFunctionalTests :: Asynchronous/Notifications/Expectations/main.swift
  SwiftXCTestFunctionalTests :: Asynchronous/Notifications/Handler/main.swift
  SwiftXCTestFunctionalTests :: Asynchronous/Predicates/Expectations/main.swift
  SwiftXCTestFunctionalTests :: Asynchronous/Predicates/Handler/main.swift
  SwiftXCTestFunctionalTests :: Asynchronous/Use/main.swift
  SwiftXCTestFunctionalTests :: EqualityWithAccuracy/main.swift
  SwiftXCTestFunctionalTests :: ErrorHandling/main.swift
  SwiftXCTestFunctionalTests :: FailingTestSuite/main.swift
  SwiftXCTestFunctionalTests :: FailureMessagesTestCase/main.swift
  SwiftXCTestFunctionalTests :: ListTests/main.swift
  SwiftXCTestFunctionalTests :: Observation/All/main.swift
  SwiftXCTestFunctionalTests :: Observation/MultipleObservers/main.swift
  SwiftXCTestFunctionalTests :: Observation/Selected/main.swift
  SwiftXCTestFunctionalTests :: Performance/Misuse/main.swift
  SwiftXCTestFunctionalTests :: Performance/main.swift
  SwiftXCTestFunctionalTests :: SelectedTest/main.swift
  SwiftXCTestFunctionalTests :: SingleFailingTestCase/main.swift
  SwiftXCTestFunctionalTests :: SkippingTestCase/main.swift
  SwiftXCTestFunctionalTests :: TestCaseLifecycle/Misuse/main.swift
  SwiftXCTestFunctionalTests :: TestCaseLifecycle/main.swift

Which is weird, since this is literally just test expectation changes in 3 tests not listed there 😅