riscv_sim: Pass htif exit code through to exit so we can easily test it when running tests.

Author: rmn30

c_emulator/riscv_sim.c

@@ -1053,7 +1053,7 @@ void run_sail(void)
   if (diverged) {
     /* TODO */
   }
-  finish(diverged);
+  finish(diverged | zhtif_exit_code);
 
 step_exception:
   fprintf(stderr, "Sail exception!");