Move coroutines to kotlin.coroutines package: compiler

Generate continuation type as kotlin.coroutines.Continuaion. This code will
fail at runtime since there is no stdlib backing this change yet.
However, in order to generate compatible stdlib we need a compiler, which
generates continuation type as kotlin.coroutines.Continuation.
Thus, firstly we support the change in the compiler, make it bootstrap
compiler and only then change stdlib and tests accordingly.
 #KT-23362

compiler/serialization/src/org/jetbrains/kotlin/serialization/DescriptorSerializer.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
  * that can be found in the license/LICENSE.txt file.
  */
 
@@ -502,7 +502,7 @@ class DescriptorSerializer private constructor(
         }
 
         if (type.isSuspendFunctionType) {
-            val functionType = type(transformSuspendFunctionToRuntimeFunctionType(type))
+            val functionType = type(transformSuspendFunctionToRuntimeFunctionType(type, extension.releaseCoroutines()))
             functionType.flags = Flags.getTypeFlags(true)
             return functionType
         }

compiler/serialization/src/org/jetbrains/kotlin/serialization/SerializerExtension.kt

@@ -1,17 +1,6 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.serialization
@@ -71,4 +60,6 @@ abstract class SerializerExtension {
     open fun serializeErrorType(type: KotlinType, builder: ProtoBuf.Type.Builder) {
         throw IllegalStateException("Cannot serialize error type: $type")
     }
+
+    open fun releaseCoroutines(): Boolean = false
 }