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_addrinfo.c

@@ -62,9 +62,9 @@
 #if defined(__INTEL_COMPILER) && (__INTEL_COMPILER == 910) && \
   defined(__OPTIMIZE__) && defined(__unix__) && defined(__i386__)
   /* workaround icc 9.1 optimizer issue */
-# define vqualifier volatile
+#  define vqualifier volatile
 #else
-# define vqualifier
+#  define vqualifier
 #endif
 
 void Curl_freeaddrinfo(struct Curl_addrinfo *cahead)