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/core/path.c

@@ -146,10 +146,9 @@ int path_spec_fd_event(PathSpec *s, uint32_t revents) {
         ssize_t l;
         int r = 0;
 
-        if (revents != EPOLLIN) {
-                log_error("Got invalid poll event on inotify.");
-                return -EINVAL;
-        }
+        if (revents != EPOLLIN)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "Got invalid poll event on inotify.");
 
         l = read(s->inotify_fd, &buffer, sizeof(buffer));
         if (l < 0) {