pan/bi: Factor out singleton construction from scheduler

We'll reuse the logic in spilling.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7206>
diff --git a/src/panfrost/bifrost/compiler.h b/src/panfrost/bifrost/compiler.h
index 47c1099..f811629 100644
--- a/src/panfrost/bifrost/compiler.h
+++ b/src/panfrost/bifrost/compiler.h
@@ -655,6 +655,12 @@
 void bi_schedule(bi_context *ctx);
 void bi_register_allocate(bi_context *ctx);
 
+bi_clause *bi_make_singleton(void *memctx, bi_instruction *ins,
+                bi_block *block,
+                unsigned scoreboard_id,
+                unsigned dependencies,
+                bool osrb);
+
 /* Liveness */
 
 void bi_compute_liveness(bi_context *ctx);