IR: compute correct IR-based mangles for Java fields

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/mangle/ir/IrMangleComputer.kt

@@ -256,8 +256,15 @@ abstract class IrMangleComputer(protected val builder: StringBuilder, private va
         typeParameters.collectForMangler(builder, MangleConstant.TYPE_PARAMETERS) { mangleTypeParameter(this, it) }
 
         builder.append(declaration.name.asString())
+
+        if (declaration.isSyntheticForJavaField) {
+            builder.append(MangleConstant.JAVA_FIELD_SUFFIX)
+        }
     }
 
+    private val IrProperty.isSyntheticForJavaField: Boolean
+        get() = origin == IrDeclarationOrigin.IR_EXTERNAL_JAVA_DECLARATION_STUB && getter == null && setter == null
+
     override fun visitField(declaration: IrField) {
         val prop = declaration.correspondingPropertySymbol
         if (compatibleMode || prop == null) { // act as used to be (KT-48912)