Add FIO_SIGQUIT engine option

For network engines, we need a signal to make it abort the connection
if it isn't already running. Otherwise fio would just stall on ctrl-c
before the connection was established.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.h b/fio.h
index 6dbc4cd..9c90024 100644
--- a/fio.h
+++ b/fio.h
@@ -263,6 +263,7 @@
 	FIO_NODISKUTIL  = 1 << 4,       /* diskutil can't handle filename */
 	FIO_UNIDIR	= 1 << 5,	/* engine is uni-directional */
 	FIO_NOIO	= 1 << 6,	/* thread does only pseudo IO */
+	FIO_SIGQUIT	= 1 << 7,	/* needs SIGQUIT to exit */
 };
 
 enum fio_file_flags {