examples: fix build issues in 'complicated' examples

- cacertinmem: build cleanly with BoringSSL/AWS-LC.
- cacertinmem: silence `-Wcast-function-type-strict`.
- multi-uv: fix callback prototypes.
- multithread, threaded-ssl: do not pass const as thread arg.
- sessioninfo: fix suppressing deprecated feature warning.
- usercertinmem: sync formatting with cacertinmem.

Follow-up to 4a6bdd5899 #18908
Cherry-picked from #18909
Closes #18914

docs/examples/multithread.c

@@ -48,12 +48,13 @@ static const char * const urls[NUMT]= {
   "www.example"
 };
 
-static void *pull_one_url(void *url)
+static void *pull_one_url(void *pindex)
 {
+  int i = *(int *)pindex;
   CURL *curl;
 
   curl = curl_easy_init();
-  curl_easy_setopt(curl, CURLOPT_URL, url);
+  curl_easy_setopt(curl, CURLOPT_URL, urls[i]);
   curl_easy_perform(curl); /* ignores error */
   curl_easy_cleanup(curl);
 
@@ -79,7 +80,7 @@ int main(void)
     int error = pthread_create(&tid[i],
                                NULL, /* default attributes please */
                                pull_one_url,
-                               (void *)urls[i]);
+                               (void *)&i);
     if(error)
       fprintf(stderr, "Couldn't run thread number %d, errno %d\n", i, error);
     else