[K/N] Remove FixmeConcurrency annotation

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

@@ -6,7 +6,6 @@
 package kotlin
 
 import kotlin.native.concurrent.*
-import kotlin.native.internal.FixmeConcurrency
 import kotlin.reflect.KProperty
 import kotlin.native.isExperimentalMM
 
@@ -37,7 +36,6 @@ public actual fun <T> lazy(initializer: () -> T): Lazy<T> =
  * to synchronize on. Do not synchronize from external code on the returned instance as it may cause accidental deadlock.
  * Also this behavior can be changed in the future.
  */
-@FixmeConcurrency
 @OptIn(kotlin.ExperimentalStdlibApi::class, FreezingIsDeprecated::class)
 public actual fun <T> lazy(mode: LazyThreadSafetyMode, initializer: () -> T): Lazy<T> =
         when (mode) {
@@ -57,6 +55,5 @@ public actual fun <T> lazy(mode: LazyThreadSafetyMode, initializer: () -> T): La
  * in this case do not synchronize from external code on the returned instance as it may cause accidental deadlock.
  * Also this behavior can be changed in the future.
  */
-@FixmeConcurrency
 @Suppress("UNUSED_PARAMETER")
 public actual fun <T> lazy(lock: Any?, initializer: () -> T): Lazy<T> = throw UnsupportedOperationException()

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

@@ -81,13 +81,6 @@ internal annotation class ExportTypeInfo(val name: String)
 @Retention(AnnotationRetention.BINARY)
 internal annotation class VolatileLambda
 
-/**
- * Need to be fixed because of concurrency.
- */
-@Target(AnnotationTarget.FUNCTION, AnnotationTarget.CLASS)
-@Retention(AnnotationRetention.SOURCE)
-internal annotation class FixmeConcurrency
-
 /**
  * Escape analysis annotations.
  */

kotlin-native/runtime/src/main/kotlin/kotlin/sequences/Sequences.kt

@@ -6,9 +6,7 @@
 package kotlin.sequences
 
 import kotlin.comparisons.*
-import kotlin.native.internal.FixmeConcurrency
 
-@FixmeConcurrency
 internal actual class ConstrainedOnceSequence<T> actual constructor(sequence: Sequence<T>) : Sequence<T> {
     // TODO: not MT friendly.
     private var sequenceRef : Sequence<T>? = sequence