[String] Add _CocoaString typealias to all build configurations.

Conditionally compiling out _CocoaString from 32-bit string will be
way too unweidly. Fixes Android bots.

Author: milseman

stdlib/public/core/StringBridge.swift

@@ -12,14 +12,15 @@
 
 import SwiftShims
 
+/// Effectively an untyped NSString that doesn't require foundation.
+@usableFromInline
+internal typealias _CocoaString = AnyObject
+
 #if _runtime(_ObjC)
 // Swift's String bridges NSString via this protocol and these
 // variables, allowing the core stdlib to remain decoupled from
 // Foundation.
 
-/// Effectively an untyped NSString that doesn't require foundation.
-public typealias _CocoaString = AnyObject
-
 @usableFromInline // @testable
 @_effects(releasenone)
 internal func _stdlib_binary_CFStringCreateCopy(