tidy-up: miscellaneous

- vms/curlmsg_vms.h: delete unused/commented code.
- vtls/schannel_verify: sort includes.
- typecheck-gcc.h: fix indent and alignment.
- lib/config-win32.h: drop idle `#undef`.
- spacecheck: check for stray empty lines before after curly braces.
- make literals more readable: 1048576 -> 1024 * 1024
- scope variables.
- use ISO date in a comment.
- drop redundant parentheses.
- drop empty comments.
- unfold lines.
- duplicate/stray spaces in comments.
- fix indent, whitespace, minor typos.

Closes #20690

docs/examples/externalsocket.c

@@ -100,7 +100,7 @@ int main(void)
 {
   CURL *curl;
   CURLcode result;
-  struct sockaddr_in servaddr;  /*  socket address structure  */
+  struct sockaddr_in servaddr;  /* socket address structure */
   curl_socket_t sockfd;
 
   result = curl_global_init(CURL_GLOBAL_ALL);
@@ -141,7 +141,7 @@ int main(void)
     /* no progress meter please */
     curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 1L);
 
-    /* send all data to this function  */
+    /* send all data to this function */
     curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_cb);
 
     /* call this function to get a socket */