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

docs/examples/multi-debugcallback.c

@@ -42,7 +42,7 @@ static void dump(const char *text, const unsigned char *ptr,
     /* without the hex output, we can fit more on screen */
     width = 0x40;
 
-  fprintf(stderr, "%s, %10.10lu bytes (0x%8.8lx)\n",
+  fprintf(stderr, "%s, %lu bytes (0x%lx)\n",
           text, (unsigned long)size, (unsigned long)size);
 
   for(i = 0; i < size; i += width) {