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/chkspeed.c

@@ -172,7 +172,7 @@ int main(int argc, const char *argv[])
     /* specify URL to get */
     curl_easy_setopt(curl, CURLOPT_URL, url);
 
-    /* send all data to this function  */
+    /* send all data to this function */
     curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_cb);
 
     /* some servers do not like requests that are made without a user-agent