trigger: enable separate remote and local trigger

Change the options so that we have the trigger file and command
separate, and remote and local trigger command separate as well.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fio.h b/fio.h
index 50cf1b0..0601b37 100644
--- a/fio.h
+++ b/fio.h
@@ -393,6 +393,7 @@
 extern pthread_cond_t helper_cond;
 extern char *trigger_file;
 extern char *trigger_cmd;
+extern char *trigger_remote_cmd;
 extern long long trigger_timeout;
 
 extern struct thread_data *threads;