Fix usage of descriptor API

(cherry picked from commit 71abe130dcc97fdf9e64e272bb4b24cb94bdb46f)

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/IrToBitcode.kt

@@ -67,7 +67,7 @@ internal fun IrClass.storageKind(context: Context): ObjectStorageKind = when {
 }
 
 val IrField.isMainOnlyNonPrimitive get() = when  {
-        descriptor.type.computePrimitiveBinaryTypeOrNull() != null -> false
+        type.computePrimitiveBinaryTypeOrNull() != null -> false
         else -> storageKind == FieldStorageKind.MAIN_THREAD
     }