initctl: don't eat up error code

src/initctl/initctl.c

@@ -218,7 +218,7 @@ static int fifo_process(Fifo *f) {
                         return 0;
 
                 log_warning("Failed to read from fifo: %m");
-                return -1;
+                return -errno;
         }
 
         f->bytes_read += l;