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/util.py

@@ -29,10 +29,8 @@ import re
 
 log = logging.getLogger(__name__)
 
-
 REPLY_DATA = re.compile("<reply>[ \t\n\r]*<data[^<]*>(.*?)</data>", re.MULTILINE | re.DOTALL)
 
-
 class ClosingFileHandler(logging.StreamHandler):
     def __init__(self, filename):
         super(ClosingFileHandler, self).__init__()
@@ -82,7 +80,6 @@ class TestData(object):
         # Left-strip the data so we do not get a newline before our data.
         return m.group(1).lstrip()
 
-
 if __name__ == '__main__':
     td = TestData("./data")
     data = td.get_test_data(1451)