Support > 4 byte verify write patterns

This is the patch I have to write/read/verify hex patterns of size > 4
bytes.  I have tested these on hard drives and did not see any
performance change. I am assuming the performance drop if any might show
up in the read phase for probably solid state drives and maybe it can be
worked around using the asynchronous verify flag.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/HOWTO b/HOWTO
index aa10dbc..cdd6473 100644
--- a/HOWTO
+++ b/HOWTO
@@ -846,13 +846,14 @@
 			size of header_interval. blocksize should divide this
 			evenly.
 
-verify_pattern=int	If set, fio will fill the io buffers with this
+verify_pattern=str	If set, fio will fill the io buffers with this
 		pattern. Fio defaults to filling with totally random
 		bytes, but sometimes it's interesting to fill with a known
 		pattern for io verification purposes. Depending on the
 		width of the pattern, fio will fill 1/2/3/4 bytes of the
-		buffer at the time. The verify_pattern cannot be larger than
-		a 32-bit quantity.
+		buffer at the time(it can be either a decimal or a hex number).
+		The verify_pattern if larger than a 32-bit quantity has to
+		be a hex number that starts with either "0x" or "0X".
 
 verify_fatal=bool	Normally fio will keep checking the entire contents
 		before quitting on a block verification failure. If this