tidy-up: miscellaneous

- examples: sync debug output printf masks.
- INSTALL-CMAKE.md: tidy up section for some options.
- curl_sha512_256: delete comment suggesting an optimization.
- vtls/keylog: scope a variable.
- vtls/openssl: make a source code URL a permalink.
- vtls/schannel: drop redundant parentheses.
- test1119.pl: robustify `$1` -> `$s`.
- sync arg names in comments to match the code.
- tidy up and minor fixes to comments.
- fix formatting/indenting/comment/newline/include nits.
- move `UNITTEST` protos next to definitions, sync their argument names.
- make variables static.
- add parentheses to Perl `open()` calls.
- drop unnecessary double quotes in Perl.
- clang-format.

Closes #21000

lib/curl_threads.h

@@ -65,8 +65,8 @@ CURLcode Curl_cond_timedwait(curl_cond_t *c, curl_mutex_t *m,
 
 #ifdef USE_THREADS
 
-curl_thread_t Curl_thread_create(CURL_THREAD_RETURN_T
-                                 (CURL_STDCALL *func) (void *), void *arg);
+curl_thread_t Curl_thread_create(
+  CURL_THREAD_RETURN_T(CURL_STDCALL *func)(void *), void *arg);
 
 void Curl_thread_destroy(curl_thread_t *hnd);