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

compiler/testData/codegen/light-analysis/delegatedProperty/setAsExtensionFunInClass.txt

@@ -1,3 +1,4 @@
+@kotlin.Metadata
 public final class A {
     private synthetic final static field $$delegatedProperties: kotlin.reflect.KProperty[]
     private final @org.jetbrains.annotations.NotNull field prop$delegate: Delegate
@@ -7,6 +8,7 @@ public final class A {
     public final method setValue(@org.jetbrains.annotations.NotNull p0: Delegate, @org.jetbrains.annotations.Nullable p1: java.lang.Object, @org.jetbrains.annotations.NotNull p2: kotlin.reflect.KProperty, p3: int): void
 }
 
+@kotlin.Metadata
 public final class Delegate {
     private field inner: int
     public method <init>(): void
@@ -15,6 +17,7 @@ public final class Delegate {
     public final method setInner(p0: int): void
 }
 
+@kotlin.Metadata
 public final class SetAsExtensionFunInClassKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }