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

compiler/testData/codegen/light-analysis/when/enumOptimization/manyWhensWithinClass.txt

@@ -1,3 +1,4 @@
+@kotlin.Metadata
 public final class A {
     public method <init>(): void
     public final @org.jetbrains.annotations.NotNull method bar1(@org.jetbrains.annotations.NotNull p0: Season): java.lang.String
@@ -5,10 +6,12 @@ public final class A {
     private final method bar3(p0: Season, p1: kotlin.jvm.functions.Function1): java.lang.String
 }
 
+@kotlin.Metadata
 public final class ManyWhensWithinClassKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }
 
+@kotlin.Metadata
 public enum class Season {
     public final static field AUTUMN: Season
     public final static field SPRING: Season