[Stdlib] Silence all warnings about deprecated @objc inference.

This eliminates 26 Objective-C entry points that we never intended to expose, but that came “for free” with the @objc inference rules.

stdlib/public/core/Runtime.swift.gyb

@@ -492,7 +492,7 @@ class _SwiftNativeNSEnumerator {}
 // FIXME(ABI)#60 : move into the Foundation overlay and remove 'open'
 @objc @_swift_native_objc_runtime_base(_SwiftNativeNSDataBase)
 open class _SwiftNativeNSData {
-  public init() {}
+  @objc public init() {}
 }
 
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