[stdlib] Mark _move as public.

Just a thinko on my part.

Author: gottesmm

stdlib/public/core/LifetimeManager.swift

@@ -187,7 +187,7 @@ extension String {
 @inlinable
 @_transparent
 @_semantics("lifetimemanagement.move")
-func _move<T>(_ value: __owned T) -> T {
+public func _move<T>(_ value: __owned T) -> T {
     #if $BuiltinMove
         Builtin.move(value)
     #else

test/stdlib/LifetimeManagement.swift

@@ -13,4 +13,9 @@ suite.test("copy") {
   expectTrue(k === _copy(k))
 }
 
-runAllTests()
+suite.test("move") {
+  let k = Klass()
+  expectTrue(k === _move(k))
+}
+
+runAllTests()