Handle percentile lists with higher precision that 2 digits

We cap the output at %2.2f right now, that's not always enough.
Make the parser check and store the precision required to
output the list correctly.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/stat.h b/stat.h
index 97186c1..98ae4c8 100644
--- a/stat.h
+++ b/stat.h
@@ -144,6 +144,7 @@
 	 * IO depth and latency stats
 	 */
 	uint64_t clat_percentiles;
+	uint64_t percentile_precision;
 	fio_fp64_t percentile_list[FIO_IO_U_LIST_MAX_LEN];
 
 	uint32_t io_u_map[FIO_IO_U_MAP_NR];