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/path/path.c

@@ -100,8 +100,8 @@ static int print_home(const char *n) {
                 }
         }
 
-        log_error("Path %s not known.", n);
-        return -EOPNOTSUPP;
+        return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP),
+                               "Path %s not known.", n);
 }
 
 static int help(void) {