tidy-up: miscellaneous

- curl_ntlm_core, smtp, schannel: fix comments.
- curl_setup.h: fix to undef before define.
- tool_doswin, server/sockfilt: reduce variables scopes.
- tool_doswin: drop an interim variable.
- windows: replace `SOCKET_ERROR` with `0` to align with rest of code.
- libssh2: rename variable to align with rest of code.
- gtls, unit1398: use `#if 0`.
- curl_trc.h, curlx/inet_ntop.h: add missing parentheses in macro
  expressions.
- ldap.c: set empty macro to `do {} while(0)`.
- examples/crawler: rename a non-CURLcode `result` variable.
- CURLINFO_TLS_SESSION: drop stray colon.
- add `const` to casts where missing.
- drop unnecessary parentheses.
- fix indent.
- quote style.
- comment style.
- whitespace, newlines, fold/unfold.

Closes #20554

lib/socks_sspi.c

@@ -550,7 +550,7 @@ CURLcode Curl_SOCKS5_gssapi_negotiate(struct Curl_cfilter *cf,
   (void)curlx_nonblock(sock, TRUE);
 
   infof(data, "SOCKS5 access with%s protection granted BUT NOT USED.",
-        (socksreq[0] == 0) ? "out GSS-API data":
+        (socksreq[0] == 0) ? "out GSS-API data" :
         ((socksreq[0] == 1) ? " GSS-API integrity" :
          " GSS-API confidentiality"));