Remove holes in verify_header structure

Shrink the magic and verify_type members, and reorder so that
it packs nicely. Incompatible change, write workloads must be
re-run.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/verify.h b/verify.h
index ec7365c..7c238c8 100644
--- a/verify.h
+++ b/verify.h
@@ -3,8 +3,7 @@
 
 #include <stdint.h>
 
-#define FIO_HDR_MAGIC	0xf00baaef
-#define FIO_HDR_MAGIC2	0xf00dbeef
+#define FIO_HDR_MAGIC	0xacca
 
 enum {
 	VERIFY_NONE = 0,		/* no verification */
@@ -29,12 +28,10 @@
  * data.
  */
 struct verify_header {
-	uint32_t fio_magic;
+	uint16_t magic;
+	uint16_t verify_type;
 	uint32_t len;
-	uint32_t verify_type;
-	uint32_t pad1;
 	uint64_t rand_seed;
-	uint32_t pad2;
 	uint32_t crc32;
 };