coccinelle: make use of SYNTHETIC_ERRNO

Ideally, coccinelle would strip unnecessary braces too. But I do not see any
option in coccinelle for this, so instead, I edited the patch text using
search&replace to remove the braces. Unfortunately this is not fully automatic,
in particular it didn't deal well with if-else-if-else blocks and ifdefs, so
there is an increased likelikehood be some bugs in such spots.

I also removed part of the patch that coccinelle generated for udev, where we
returns -1 for failure. This should be fixed independently.

src/debug-generator/debug-generator.c

@@ -145,10 +145,9 @@ static int generate_wants_symlinks(void) {
 static int run(int argc, char *argv[]) {
         int r, q;
 
-        if (argc > 1 && argc != 4) {
-                log_error("This program takes three or no arguments.");
-                return -EINVAL;
-        }
+        if (argc > 1 && argc != 4)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "This program takes three or no arguments.");
 
         if (argc > 1)
                 arg_dest = argv[2];