Kapt3: Write stub class files with metadata (needed for incremental compilation)

compiler/testData/codegen/light-analysis/controlStructures/forLoopMemberExtensionNext.txt

@@ -1,13 +1,16 @@
+@kotlin.Metadata
 public final class C {
     public method <init>(): void
     public final @org.jetbrains.annotations.NotNull method iterator(): It
 }
 
+@kotlin.Metadata
 public final class ForLoopMemberExtensionNextKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
     public final static method foo(p0: int): void
 }
 
+@kotlin.Metadata
 public final class It {
     private field hasNext: boolean
     public method <init>(): void
@@ -16,6 +19,7 @@ public final class It {
     public final method setHasNext(p0: boolean): void
 }
 
+@kotlin.Metadata
 public final class X {
     public method <init>(): void
     public final method next(@org.jetbrains.annotations.NotNull p0: It): int