[stdlib] Optional, Result: Update borrowing switch syntax (_borrowing → borrowing)

Author: lorentey

stdlib/public/core/Optional.swift

@@ -232,7 +232,7 @@ extension Optional where Wrapped: ~Copyable {
   ) throws(E) -> U? {
     #if $NoncopyableGenerics
     switch self {
-    case .some(_borrowing y):
+    case .some(borrowing y):
       return .some(try transform(y))
     case .none:
       return .none
@@ -310,7 +310,7 @@ extension Optional where Wrapped: ~Copyable {
     _ transform: (borrowing Wrapped) throws(E) -> U?
   ) throws(E) -> U? {
     switch self {
-    case .some(_borrowing y):
+    case .some(borrowing y):
       return try transform(y)
     case .none:
       return .none

stdlib/public/core/Result.swift

@@ -95,7 +95,7 @@ extension Result where Success: ~Copyable {
     _ transform: (borrowing Success) -> NewSuccess
   ) -> Result<NewSuccess, Failure> {
     switch self {
-    case .success(_borrowing success):
+    case .success(borrowing success):
       return .success(transform(success))
     case let .failure(failure):
       return .failure(failure)
@@ -233,7 +233,7 @@ extension Result where Success: ~Copyable {
     _ transform: (borrowing Success) -> Result<NewSuccess, Failure>
   ) -> Result<NewSuccess, Failure> {
     switch self {
-    case .success(_borrowing success):
+    case .success(borrowing success):
       return transform(success)
     case let .failure(failure):
       return .failure(failure)