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/urldata.h

@@ -133,7 +133,6 @@ typedef unsigned int curl_prot_t;
    input easier and better. */
 #define CURL_MAX_INPUT_LENGTH 8000000
 
-
 #include "cookie.h"
 #include "psl.h"
 #include "formdata.h"