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/sysctl/sysctl.c

@@ -256,10 +256,9 @@ static int parse_argv(int argc, char *argv[]) {
                         assert_not_reached("Unhandled option");
                 }
 
-        if (arg_cat_config && argc > optind) {
-                log_error("Positional arguments are not allowed with --cat-config");
-                return -EINVAL;
-        }
+        if (arg_cat_config && argc > optind)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "Positional arguments are not allowed with --cat-config");
 
         return 1;
 }