Write proto flag about compatibility mode

There is no any special aim for this flag now.
  But it could be useful in future in case of compatibility mode deprecation

compiler/backend/src/org/jetbrains/kotlin/codegen/serialization/JvmSerializerExtension.kt

@@ -94,7 +94,13 @@ class JvmSerializerExtension @JvmOverloads constructor(
         writeVersionRequirementForJvmDefaultIfNeeded(descriptor, proto, versionRequirementTable)
 
         if (jvmDefaultMode.forAllMethodsWithBody && isInterface(descriptor)) {
-            proto.setExtension(JvmProtoBuf.jvmClassFlags, JvmFlags.getClassFlags(true))
+            proto.setExtension(
+                JvmProtoBuf.jvmClassFlags,
+                JvmFlags.getClassFlags(
+                    jvmDefaultMode.forAllMethodsWithBody,
+                    JvmDefaultMode.ALL_COMPATIBILITY == jvmDefaultMode
+                )
+            )
         }
     }
 

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/FirJvmSerializerExtension.kt

@@ -95,7 +95,13 @@ class FirJvmSerializerExtension @JvmOverloads constructor(
         writeVersionRequirementForJvmDefaultIfNeeded(klass, proto, versionRequirementTable)
 
         if (jvmDefaultMode.forAllMethodsWithBody && klass is FirRegularClass && klass.classKind == ClassKind.INTERFACE) {
-            proto.setExtension(JvmProtoBuf.jvmClassFlags, JvmFlags.getClassFlags(true))
+            proto.setExtension(
+                JvmProtoBuf.jvmClassFlags,
+                JvmFlags.getClassFlags(
+                    jvmDefaultMode.forAllMethodsWithBody,
+                    JvmDefaultMode.ALL_COMPATIBILITY == jvmDefaultMode
+                )
+            )
         }
     }