[K/N] Mark UnhandledExceptionHook-related API as experimental

As a part of efforts to stabilize Native stdlib.

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

@@ -40,6 +40,7 @@ public class IncorrectDereferenceException : RuntimeException {
 /**
  * Typealias describing custom exception reporting hook.
  */
+@ExperimentalStdlibApi
 public typealias ReportUnhandledExceptionHook = Function1<Throwable, Unit>
 
 /**
@@ -55,6 +56,7 @@ public typealias ReportUnhandledExceptionHook = Function1<Throwable, Unit>
  * Set or default hook is also invoked by [processUnhandledException].
  * With the legacy MM the hook must be a frozen lambda so that it could be called from any thread/worker.
  */
+@ExperimentalStdlibApi
 @OptIn(FreezingIsDeprecated::class)
 public fun setUnhandledExceptionHook(hook: ReportUnhandledExceptionHook?): ReportUnhandledExceptionHook? {
     try {
@@ -66,7 +68,7 @@ public fun setUnhandledExceptionHook(hook: ReportUnhandledExceptionHook?): Repor
 
 @Suppress("CONFLICTING_OVERLOADS")
 @Deprecated("Provided for binary compatibility", level = DeprecationLevel.HIDDEN)
-@OptIn(FreezingIsDeprecated::class)
+@OptIn(FreezingIsDeprecated::class, ExperimentalStdlibApi::class)
 public fun setUnhandledExceptionHook(hook: ReportUnhandledExceptionHook): ReportUnhandledExceptionHook? {
     try {
         return UnhandledExceptionHookHolder.hook.swap(hook)

kotlin-native/runtime/src/main/kotlin/kotlin/native/internal/RuntimeUtils.kt

@@ -144,7 +144,7 @@ internal fun ReportUnhandledException(throwable: Throwable) {
 // Using object to make sure that `hook` is initialized when it's needed instead of
 // in a normal global initialization flow. This is important if some global happens
 // to throw an exception during it's initialization before this hook would've been initialized.
-@OptIn(FreezingIsDeprecated::class)
+@OptIn(FreezingIsDeprecated::class, ExperimentalStdlibApi::class)
 internal object UnhandledExceptionHookHolder {
     internal val hook: FreezableAtomicReference<ReportUnhandledExceptionHook?> =
         if (Platform.memoryModel == MemoryModel.EXPERIMENTAL) {
@@ -157,7 +157,7 @@ internal object UnhandledExceptionHookHolder {
 // TODO: Can be removed only when native-mt coroutines stop using it.
 @PublishedApi
 @ExportForCppRuntime
-@OptIn(FreezingIsDeprecated::class)
+@OptIn(FreezingIsDeprecated::class, ExperimentalStdlibApi::class)
 internal fun OnUnhandledException(throwable: Throwable) {
     val handler = UnhandledExceptionHookHolder.hook.value
     if (handler == null) {
@@ -172,7 +172,7 @@ internal fun OnUnhandledException(throwable: Throwable) {
 }
 
 @ExportForCppRuntime("Kotlin_runUnhandledExceptionHook")
-@OptIn(FreezingIsDeprecated::class)
+@OptIn(FreezingIsDeprecated::class, ExperimentalStdlibApi::class)
 internal fun runUnhandledExceptionHook(throwable: Throwable) {
     val handler = UnhandledExceptionHookHolder.hook.value ?: throw throwable
     handler(throwable)