Clang-Tidy fixes (#6725)

(cherry picked from commit 3c501b963d)

test/torturethread.c

@@ -52,7 +52,7 @@ ThreadFunc(void *data)
 
     for (i = 0; i < NUMTHREADS; i++) {
         char name[64];
-        SDL_snprintf(name, sizeof(name), "Child%d_%d", tid, i);
+        (void)SDL_snprintf(name, sizeof name, "Child%d_%d", tid, i);
         flags[i] = 0;
         sub_threads[i] = SDL_CreateThread(SubThreadFunc, name, &flags[i]);
     }
@@ -87,10 +87,10 @@ int main(int argc, char *argv[])
         return 1;
     }
 
-    signal(SIGSEGV, SIG_DFL);
+    (void)signal(SIGSEGV, SIG_DFL);
     for (i = 0; i < NUMTHREADS; i++) {
         char name[64];
-        SDL_snprintf(name, sizeof(name), "Parent%d", i);
+        (void)SDL_snprintf(name, sizeof name, "Parent%d", i);
         SDL_AtomicSet(&time_for_threads_to_die[i], 0);
         threads[i] = SDL_CreateThread(ThreadFunc, name, (void *)(uintptr_t)i);