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

compiler/testData/codegen/light-analysis/classes/classObjectWithPrivateGenericMember.txt

@@ -1,3 +1,4 @@
+@kotlin.Metadata
 public final class C {
     public final static field Companion: C.Companion
     inner class C/Companion
@@ -5,12 +6,14 @@ public final class C {
     public method <init>(): void
 }
 
+@kotlin.Metadata
 public final static class C/Companion {
     inner class C/Companion
     private method <init>(): void
     private final method create(): C
 }
 
+@kotlin.Metadata
 public final static class C/ZZZ {
     private final @org.jetbrains.annotations.NotNull field c: C
     inner class C/ZZZ
@@ -18,6 +21,7 @@ public final static class C/ZZZ {
     public final @org.jetbrains.annotations.NotNull method getC(): C
 }
 
+@kotlin.Metadata
 public final class ClassObjectWithPrivateGenericMemberKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }