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

compiler/testData/codegen/light-analysis/reflection/call/equalsHashCodeToString.txt

@@ -1,7 +1,9 @@
+@kotlin.Metadata
 public final class A {
     public method <init>(): void
 }
 
+@kotlin.Metadata
 public final class D {
     private final @org.jetbrains.annotations.NotNull field s: java.lang.String
     public method <init>(@org.jetbrains.annotations.NotNull p0: java.lang.String): void
@@ -14,6 +16,7 @@ public final class D {
     public method toString(): java.lang.String
 }
 
+@kotlin.Metadata
 public final class EqualsHashCodeToStringKt {
     public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
 }