Make fields for storing lambda parameters non-final

Because they get assigned within `invoke` call that contradicts with JVM spec
where it's told that they must not be assigned outside of constructors

compiler/backend/src/org/jetbrains/kotlin/codegen/coroutines/CoroutineCodegen.kt

@@ -59,7 +59,7 @@ class CoroutineCodegen(
         for (parameter in funDescriptor.valueParameters) {
             v.newField(
                     OtherOrigin(parameter),
-                    Opcodes.ACC_PRIVATE or Opcodes.ACC_FINAL,
+                    Opcodes.ACC_PRIVATE,
                     COROUTINE_LAMBDA_PARAMETER_PREFIX + parameter.index,
                     typeMapper.mapType(parameter.type).descriptor, null, null)
         }

compiler/testData/codegen/bytecodeListing/coroutineFields.txt

@@ -10,8 +10,8 @@ final class CoroutineFieldsKt$box$1 {
     private field J$0: long
     private field L$0: java.lang.Object
     private field L$1: java.lang.Object
-    private final field p$0: java.lang.String
-    private final field p$1: long
+    private field p$0: java.lang.String
+    private field p$1: long
     inner class CoroutineFieldsKt$box$1
     method <init>(p0: kotlin.jvm.internal.Ref$ObjectRef): void
     protected final method doResume(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.Nullable p1: java.lang.Throwable): void