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

docs/examples/http2-upload.c

@@ -67,7 +67,7 @@
 #endif
 
 #ifdef _MSC_VER
-#define gettimeofday(a, b) my_gettimeofday((a), (b))
+#define gettimeofday(a, b) my_gettimeofday(a, b)
 static int my_gettimeofday(struct timeval *tp, void *tzp)
 {
   (void)tzp;