Foundation: workaround the frontend trying to keep sugar

The compiler is working hard to keep the type sugar on the interface for
even an internal interface.  The type sugar being preserved causes a
deserialization failure on Darwin.  Use an equivalent local typealias to
avoid the issue.  SR-9811

Author: compnerd

Foundation/NSLock.swift

@@ -133,7 +133,7 @@ extension NSLock {
 open class NSConditionLock : NSObject, NSLocking {
     internal var _cond = NSCondition()
     internal var _value: Int
-    internal var _thread: _CFThreadRef?
+    internal var _thread: _swift_CFThreadRef?
 
     public convenience override init() {
         self.init(condition: 0)

Foundation/Thread.swift

@@ -9,6 +9,13 @@
 
 import CoreFoundation
 
+// WORKAROUND_SR9811
+#if os(Windows)
+internal typealias _swift_CFThreadRef = HANDLE
+#else
+internal typealias _swift_CFThreadRef = pthread_t
+#endif
+
 internal class NSThreadSpecific<T: NSObject> {
     private var key = _CFThreadSpecificKeyCreate()
 
@@ -178,7 +185,7 @@ open class Thread : NSObject {
     }
 
     internal var _main: () -> Void = {}
-    private var _thread: _CFThreadRef? = nil
+    private var _thread: _swift_CFThreadRef? = nil
 
 #if os(Windows) && !CYGWIN
     internal var _attr: _CFThreadAttributes =
@@ -194,7 +201,7 @@ open class Thread : NSObject {
 
     open private(set) var threadDictionary: NSMutableDictionary = NSMutableDictionary()
 
-    internal init(thread: _CFThreadRef) {
+    internal init(thread: _swift_CFThreadRef) {
         // Note: even on Darwin this is a non-optional _CFThreadRef; this is only used for valid threads, which are never null pointers.
         _thread = thread
     }