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/telnet.c

@@ -1266,9 +1266,9 @@ static CURLcode telnet_do(struct Curl_easy *data, bool *done)
 
 #ifdef USE_WINSOCK
   /* We want to wait for both stdin and the socket. Since
-  ** the select() function in Winsock only works on sockets
-  ** we have to use the WaitForMultipleObjects() call.
-  */
+   * the select() function in Winsock only works on sockets
+   * we have to use the WaitForMultipleObjects() call.
+   */
 
   /* First, create a sockets event object */
   event_handle = WSACreateEvent();