Add log_info_flush()

If fio dumps status through -USR1 or similar and output is
being stored in a file, the buffering on the file descriptor
by the library can cause is not to see all the output. Ensure
that it gets flushed after dumping stats.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/stat.c b/stat.c
index 7ff7ad4..03a45fc 100644
--- a/stat.c
+++ b/stat.c
@@ -1354,6 +1354,7 @@
 		show_idle_prof_stats(FIO_OUTPUT_NORMAL, NULL);
 	}
 
+	log_info_flush();
 	free(runstats);
 	free(threadstats);
 }