Remove redundant @OptIn

kotlin-native/Interop/Runtime/src/main/kotlin/kotlinx/cinterop/Utils.kt

@@ -571,7 +571,6 @@ public fun CPointer<IntVar>.toKStringFromUtf32(): String {
  *
  * Malformed byte sequences are replaced by the replacement char `\uFFFD`.
  */
-@OptIn(ExperimentalStdlibApi::class)
 @SinceKotlin("1.3")
 public fun ByteArray.toKString() : String {
     val realEndIndex = realEndIndex(this, 0, this.size)
@@ -590,7 +589,6 @@ public fun ByteArray.toKString() : String {
  * @throws IllegalArgumentException if [startIndex] is greater than [endIndex].
  * @throws CharacterCodingException if the byte array contains malformed UTF-8 byte sequence and [throwOnInvalidSequence] is true.
  */
-@OptIn(ExperimentalStdlibApi::class)
 @SinceKotlin("1.3")
 public fun ByteArray.toKString(
         startIndex: Int = 0,

kotlin-native/runtime/src/main/kotlin/kotlin/collections/ArrayList.kt

@@ -141,7 +141,6 @@ actual class ArrayList<E> private constructor(
             array = array.copyOfUninitializedElements(length)
     }
 
-    @OptIn(ExperimentalStdlibApi::class)
     final actual fun ensureCapacity(minCapacity: Int) {
         if (backing != null) throw IllegalStateException() // just in case somebody casts subList to ArrayList
         if (minCapacity > array.size) {

kotlin-native/runtime/src/main/kotlin/kotlin/collections/HashMap.kt

@@ -470,10 +470,8 @@ actual class HashMap<K, V> private constructor(
         private const val INITIAL_MAX_PROBE_DISTANCE = 2
         private const val TOMBSTONE = -1
 
-        @OptIn(ExperimentalStdlibApi::class)
         private fun computeHashSize(capacity: Int): Int = (capacity.coerceAtLeast(1) * 3).takeHighestOneBit()
 
-        @OptIn(ExperimentalStdlibApi::class)
         private fun computeShift(hashSize: Int): Int = hashSize.countLeadingZeroBits() + 1
     }