bug#70474: [PATCH 1/2] Including the cast makes Apple clang 15.0.0 happy; without it, clang is sad

I'm not sure why, exactly, but I needed this to get builds to work on 
OSX Sonoma at all.

---
  libguile/scmsigs.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libguile/scmsigs.c b/libguile/scmsigs.c
index 7fd3fd8f1..be96dbd5c 100644
--- a/libguile/scmsigs.c
+++ b/libguile/scmsigs.c
@@ -302,7 +302,7 @@ scm_i_signals_post_fork ()
      }
   #if SCM_USE_PTHREAD_THREADS
-  once = SCM_I_PTHREAD_ONCE_INIT;
+  once = (scm_i_pthread_once_t) SCM_I_PTHREAD_ONCE_INIT;
  #endif
    if (active)
      scm_i_ensure_signal_delivery_thread ();
-- 
2.44.0