JVM_IR: serialize fake overrides in IR

compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/JvmIrSerializer.kt

@@ -26,6 +26,9 @@ class JvmIrSerializer(
 
     // Usage protocol: construct an instance, call only one of `serializeIrFile()` and `serializeTopLevelClass()` only once.
 
+    // We do not reconstruct fake overrides upon deserialization (yet).
+    override fun backendSpecificSerializeAllMembers(irClass: IrClass): Boolean = true
+
     fun serializeJvmIrFile(irFile: IrFile): JvmIr.JvmIrFile {
         val proto = JvmIr.JvmIrFile.newBuilder()