stat: add dropped ios to the standard output

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/stat.h b/stat.h
index 90a7fb3..1727c0c 100644
--- a/stat.h
+++ b/stat.h
@@ -160,6 +160,7 @@
 	uint32_t io_u_plat[DDIR_RWDIR_CNT][FIO_IO_U_PLAT_NR];
 	uint64_t total_io_u[3];
 	uint64_t short_io_u[3];
+	uint64_t drop_io_u[3];
 	uint64_t total_submit;
 	uint64_t total_complete;