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

tests/processhelp.pm

@@ -468,7 +468,6 @@ sub killallsockfilters {
     }
 }
 
-
 sub set_advisor_read_lock {
     my ($filename) = @_;
 
@@ -479,7 +478,6 @@ sub set_advisor_read_lock {
     printf "Error creating lock file $filename error: $!\n";
 }
 
-
 sub clear_advisor_read_lock {
     my ($filename) = @_;
 
@@ -488,5 +486,4 @@ sub clear_advisor_read_lock {
     }
 }
 
-
 1;