[TaskLocals] Avoid use of defer in back deployed functions in the standard library.

Older versions of the 5.8 compiler have a bug when generating SIL for functions with `@_backDeploy` containing defer blocks (#62444) and for now we need the standard library interface to be compatible with those older compilers.

Resolves rdar://104045168

Author: tshortli

stdlib/public/BackDeployConcurrency/TaskCancellation.swift

@@ -46,9 +46,10 @@ public func withTaskCancellationHandler<T>(
   // unconditionally add the cancellation record to the task.
   // if the task was already cancelled, it will be executed right away.
   let record = _taskAddCancellationHandler(handler: handler)
-  defer { _taskRemoveCancellationHandler(record: record) }
+  let result = try await operation()
+  _taskRemoveCancellationHandler(record: record)
 
-  return try await operation()
+  return result
 }
 
 @available(SwiftStdlib 5.1, *)

stdlib/public/BackDeployConcurrency/TaskLocal.swift

@@ -145,9 +145,10 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
     _checkIllegalTaskLocalBindingWithinWithTaskGroup(file: file, line: line)
 
     _taskLocalValuePush(key: key, value: valueDuringOperation)
-    defer { _taskLocalValuePop() }
+    let result = try await operation()
+    _taskLocalValuePop()
 
-    return try await operation()
+    return result
   }
 
   /// Binds the task-local to the specific value for the duration of the

stdlib/public/Concurrency/TaskCancellation.swift

@@ -46,9 +46,10 @@ public func withTaskCancellationHandler<T>(
   // unconditionally add the cancellation record to the task.
   // if the task was already cancelled, it will be executed right away.
   let record = _taskAddCancellationHandler(handler: handler)
-  defer { _taskRemoveCancellationHandler(record: record) }
+  let result = try await operation()
+  _taskRemoveCancellationHandler(record: record)
 
-  return try await operation()
+  return result
 }
 
 @available(SwiftStdlib 5.1, *)

stdlib/public/Concurrency/TaskLocal.swift

@@ -145,9 +145,10 @@ public final class TaskLocal<Value: Sendable>: Sendable, CustomStringConvertible
     _checkIllegalTaskLocalBindingWithinWithTaskGroup(file: file, line: line)
 
     _taskLocalValuePush(key: key, value: valueDuringOperation)
-    defer { _taskLocalValuePop() }
+    let result = try await operation()
+    _taskLocalValuePop()
 
-    return try await operation()
+    return result
   }
 
   /// Binds the task-local to the specific value for the duration of the