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

src/tool_parsecfg.c

@@ -273,7 +273,6 @@ ParameterError parseconfig(const char *filename, int max_recursive,
   return err;
 }
 
-
 static bool get_line(FILE *input, struct dynbuf *buf, bool *error)
 {
   CURLcode result;