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/curl_trc.c

@@ -487,7 +487,7 @@ void Curl_trc_ws(struct Curl_easy *data, const char *fmt, ...)
 }
 #endif /* !CURL_DISABLE_WEBSOCKETS && !CURL_DISABLE_HTTP */
 
-#define TRC_CT_NONE        (0)
+#define TRC_CT_NONE        0
 #define TRC_CT_PROTOCOL    (1 << 0)
 #define TRC_CT_NETWORK     (1 << 1)
 #define TRC_CT_PROXY       (1 << 2)