Wire up SIGUSR2 to kill blocking threads

Get rid of io engine ops SIGTERM flag, it didn't really
work.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index d7cb4ab..58364aa 100644
--- a/fio.h
+++ b/fio.h
@@ -694,8 +694,8 @@
 	TD_NOT_CREATED = 0,
 	TD_CREATED,
 	TD_INITIALIZED,
-	TD_SETTING_UP,
 	TD_RAMP,
+	TD_SETTING_UP,
 	TD_RUNNING,
 	TD_PRE_READING,
 	TD_VERIFYING,