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

tests/sshserver.pl

@@ -446,21 +446,21 @@ if((! -e pp($hstprvkeyf)) || (! -s pp($hstprvkeyf)) ||
     my @rsahostkey = do { local $/ = ' '; <$rsakeyfile> };
     close($rsakeyfile);
     if(!$rsahostkey[1]) {
-        logmsg "Failed parsing base64 encoded RSA host key\n";
+        logmsg "Failed parsing base64 encoded SSH host key\n";
         exit 1;
     }
     open(my $pubmd5file, ">", pp($hstpubmd5f));
     print $pubmd5file md5_hex(decode_base64($rsahostkey[1]));
     close($pubmd5file);
     if((! -e pp($hstpubmd5f)) || (! -s pp($hstpubmd5f))) {
-        logmsg "Failed writing md5 hash of RSA host key\n";
+        logmsg "Failed writing MD5 hash of SSH host key\n";
         exit 1;
     }
     open(my $pubsha256file, ">", pp($hstpubsha256f));
     print $pubsha256file sha256_base64(decode_base64($rsahostkey[1]));
     close($pubsha256file);
     if((! -e pp($hstpubsha256f)) || (! -s pp($hstpubsha256f))) {
-        logmsg "Failed writing sha256 hash of RSA host key\n";
+        logmsg "Failed writing SHA256 hash of SSH host key\n";
         exit 1;
     }
 }