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

scripts/ciconfig.pl

@@ -108,7 +108,6 @@ my %defaulton = (
 
     );
 
-
 sub configureopts {
     my ($opts)=@_;
     my %thisin;
@@ -189,7 +188,6 @@ for my $w (sort keys %avail) {
     }
 }
 
-
 print "ENABLED configure options that are not available\n";
 for my $w (sort keys %with) {
     if(!$avail{$w}) {