tidy-up: miscellaneous

- drop stray duplicate empty lines in docs, scripts, test data, include,
  examples, tests.
- drop duplicate PP parenthesis.
- curl-functions.m4: move literals to the right side in if expressions,
  to match rest of the source code.
- FAQ.md: delete language designator from an URL.
- packages: apply clang-format (OS400, VMS).
- scripts/schemetable.c: apply clang-format.
- data320: delete duplicate empty line that doesn't change the outcome.
- spacecheck: extend to check for duplicate empty lines
  (with exceptions.)
- fix whitespace nits

Closes #19936

lib/http.h

@@ -213,7 +213,6 @@ Curl_http_output_auth(struct Curl_easy *data,
 /* Decode HTTP status code string. */
 CURLcode Curl_http_decode_status(int *pstatus, const char *s, size_t len);
 
-
 /**
  * All about a core HTTP request, excluding body and trailers
  */