Fix TimeZone does not conforms to _ObjectiveCBridgeable

[dreampiggy]

PR description

This PR fix the missing _ObjectiveCBridgeable protocol conformance on TimeZone struct.

The API in Apple's Foundation declares TimeZone is marked as here:

So this seems a typo, not designed behavior.

Environment

Platform: Linux
Docker Image: swift/latest d8708e4f244e2fa11eb9d1f4d718ee0a8481807f0070a7c5f9da5c2f853a94e5
Swift Version: Swift version 5.5.2 (swift-5.5.2-RELEASE)

Demo Code

public protocol NSObjectBridgeable : _ObjectiveCBridgeable {}
extension TimeZone : NSObjectBridgeable {}

Excepted Result

Build Success.

Actual Result

Build Failure. Showing:

error: conformance of 'TimeZone' to '_ObjectiveCBridgeable' can only be written in module 'Foundation'
extension TimeZone : NSObjectBridgeable {}
^

[dreampiggy]

@swift-ci please test

[Kyle-Ye]

@swift-ci please test

[dreampiggy]

@swift-ci please test macOS platform

[Kyle-Ye]

@swift-ci please test Linux platform

[Kyle-Ye]

@swift-ci Please test Linux platform

[Kyle-Ye]

@swift-ci Please test Linux platform

[millenomi]

@swift-ci please test

[compnerd]

Please test with following PRs:
swiftlang/swift#41115

@swift-ci please test macOS platform