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/md5.c

@@ -548,7 +548,7 @@ CURLcode Curl_md5it(unsigned char *output,
   result = my_md5_init(&ctx);
   if(!result) {
     do {
-      unsigned int ilen = (unsigned int) CURLMIN(len, UINT_MAX);
+      unsigned int ilen = (unsigned int)CURLMIN(len, UINT_MAX);
       my_md5_update(&ctx, input, ilen);
       input += ilen;
       len -= ilen;