SR-10717: var kind: XMLNode.Kind { get } should return a correct value on Linux.

[YOCKOW]

As shown below, some kinds of nodes return incorrect values as var kind: XMLNode.Kind. This PR fixes the issue.

print((XMLNode.processingInstruction(withName: "name", stringValue: "value") as? XMLNode)?.kind == .processingInstruction)
// -> Prints "true" on macOS.
// -> Prints "false" on Linux.

print((XMLNode.comment(withStringValue: "comment") as? XMLNode)?.kind == .comment)
// -> Prints "true" on macOS.
// -> Prints "false" on Linux.

print((XMLNode.text(withStringValue: "text") as? XMLNode)?.kind == .text)
// -> Prints "true" on macOS.
// -> Prints "false" on Linux.

print(XMLDTDNode(xmlString: #"<!NOTATION f SYSTEM "F">"#)?.kind == .notationDeclaration)
// -> Prints "true" on macOS.
// -> Prints "false" on Linux.

Resolves SR-10717.

[millenomi]

@swift-ci please test

[YOCKOW]

Is the failure on Linux caused by this fix...?

[spevans]

The build failure is unrelated to this fix.

[spevans]

@swift-ci test

[YOCKOW]

Another error again.
By the way, can't anyone like me trigger "@swift-ci test"?

[spevans]

@swift-ci test linux

[spevans]

@YOCKOW See https://github.com/apple/swift/blob/master/docs/ContinuousIntegration.md#swift-ci about having access to trigger CI requests.

[YOCKOW]

@spevans
Thank you for the answer, and please forgive me for having overlooked the document.

[spevans]

@swift-ci test linux