Advance ObsoleteNativeApi opt-in requirement level to ERROR #KT-57088

As a part of efforts to stabilize Native stdlib.

kotlin-native/runtime/src/main/kotlin/kotlin/native/ObsoleteNativeApi.kt

@@ -11,13 +11,12 @@ import kotlin.annotation.AnnotationTarget.*
  * This annotation marks the Kotlin/Native standard library API that is considered obsolete and is being phased out.
  *
  * An obsolete API is not recommended to use, and users should migrate from it.
- * In the future the opt-in level of the annotation might be raised to [ERROR][RequiresOptIn.Level.ERROR].
  *
  * Any usage of a declaration annotated with `@ObsoleteNativeApi` must be accepted either by
  * annotating that usage with the [OptIn] annotation, e.g. `@OptIn(ObsoleteNativeApi::class)`,
  * or by using the compiler argument `-opt-in=kotlin.native.ObsoleteNativeApi`.
  */
-@RequiresOptIn(message = "This API is obsolete and subject to removal in a future release.", level = RequiresOptIn.Level.WARNING)
+@RequiresOptIn(message = "This API is obsolete and subject to removal in a future release.", level = RequiresOptIn.Level.ERROR)
 @Retention(AnnotationRetention.BINARY)
 @Target(
         AnnotationTarget.CLASS,

libraries/stdlib/wasm/src/kotlin/text/regex/ObsoleteNativeApi.kt

@@ -13,7 +13,7 @@ import kotlin.annotation.AnnotationTarget.*
  * This is an internal copy of the public K/N annotation.
  * It is used to [OptIn] obsolete K/N API used in the shared native-wasm directory.
  */
-@RequiresOptIn(message = "This API is obsolete and subject to removal in a future release.", level = RequiresOptIn.Level.WARNING)
+@RequiresOptIn(message = "This API is obsolete and subject to removal in a future release.", level = RequiresOptIn.Level.ERROR)
 @Retention(AnnotationRetention.BINARY)
 @Target(
     AnnotationTarget.CLASS,