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/ephiperfifo.c

@@ -41,7 +41,6 @@ Whenever there is input into the fifo, the program reads the input as a list
 of URL's and creates some new easy handles to fetch each URL via the
 curl_multi "hiper" API.
 
-
 Thus, you can try a single URL:
   % echo http://www.yahoo.com > hiper.fifo
 

docs/examples/evhiperfifo.c

@@ -44,7 +44,6 @@ Whenever there is input into the fifo, the program reads the input as a list
 of URL's and creates some new easy handles to fetch each URL via the
 curl_multi "hiper" API.
 
-
 Thus, you can try a single URL:
   % echo http://www.yahoo.com > hiper.fifo
 

docs/examples/ghiper.c

@@ -41,7 +41,6 @@
  of URL's and creates some new easy handles to fetch each URL via the
  curl_multi "hiper" API.
 
-
  Thus, you can try a single URL:
  % echo http://www.yahoo.com > hiper.fifo
 

docs/examples/hiperfifo.c

@@ -41,7 +41,6 @@ Whenever there is input into the fifo, the program reads the input as a list
 of URL's and creates some new easy handles to fetch each URL via the
 curl_multi "hiper" API.
 
-
 Thus, you can try a single URL:
   % echo http://www.yahoo.com > hiper.fifo
 

docs/examples/htmltitle.cpp

@@ -46,9 +46,9 @@
 //
 
 #ifdef _WIN32
-#define COMPARE(a, b) (!_stricmp((a), (b)))
+#define COMPARE(a, b) (!_stricmp(a, b))
 #else
-#define COMPARE(a, b) (!strcasecmp((a), (b)))
+#define COMPARE(a, b) (!strcasecmp(a, b))
 #endif
 
 //

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;

docs/examples/postit2-formadd.c

@@ -74,7 +74,6 @@ int main(int argc, char *argv[])
                  CURLFORM_COPYCONTENTS, "postit2-formadd.c",
                  CURLFORM_END);
 
-
     /* Fill in the submit field too, even if this is rarely needed */
     curl_formadd(&formpost,
                  &lastptr,