The source project of this merge request has been removed.
Require SMP support in order to build a threaded stage1
Since commit 67738db1 a threaded stage1 is build if stage0 has a threaded RTS. However, if stage0 has no SMP support (e.g. because it is an unregisterised GHC), we then run into the problem as described in #18266 (closed). Thus, requierring also SMP support solves this issue.
Fixes #18266 (closed) and #18217