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/initctl/initctl.c

@@ -322,10 +322,9 @@ static int process_event(Server *s, struct epoll_event *ev) {
 
         assert(s);
 
-        if (!(ev->events & EPOLLIN)) {
-                log_info("Got invalid event from epoll. (3)");
-                return -EIO;
-        }
+        if (!(ev->events & EPOLLIN))
+                return log_info_errno(SYNTHETIC_ERRNO(EIO),
+                                      "Got invalid event from epoll. (3)");
 
         f = (Fifo*) ev->data.ptr;
         r = fifo_process(f);