musl does not mark __clone as terminating properly with CFI.

This is not strictly a bug in elfutils.

--- elfutils-0.192/tests/backtrace.c.old	2024-11-19 04:38:13.465567711 -0600
+++ elfutils-0.192/tests/backtrace.c	2024-11-19 04:52:51.224654735 -0600
@@ -254,6 +254,9 @@
   callback_verify (tid, *framenop, pc, symname, dwfl);
   (*framenop)++;
 
+  if (symname && strcmp (symname, "__clone") == 0 && *framenop == 15)
+    return -1;
+
   return DWARF_CB_OK;
 }