[PATCH tor v1 5/6] test/bench: Fix clang-15 complaint (unused variable)

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

clang-15 throws the following complaint:

```
  src/test/bench.c:380:14: error: variable 't' set but not used [-Werror,-Wunused-but-set-variable]
      uint32_t t=0;
               ^
  1 error generated.
```

This variable firstly introduced in commit 490e187056d8 ("Add a
benchmark for our several PRNGs."). Suppress the complaint by
casting it to `(void)`.

Cc: Nick Mathewson <nickm@torproject.org>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 src/test/bench.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/test/bench.c b/src/test/bench.c
index a76ea67eb8..8a4a998e8d 100644
--- a/src/test/bench.c
+++ b/src/test/bench.c
@@ -381,6 +381,7 @@ bench_rand_len(int len)
     for (i = 0; i < N; ++i) {
       t += tor_weak_random(&weak);
     }
+    (void)t;
     end = perftime();
     printf("weak_rand(4): %f nsec.\n", NANOCOUNT(start,end,N));
   }
-- 
Ammar Faizi