Add blk64_t type definition

This will be used for all new functions so we can gradually move
e2fsprogs to support 64 bit blocks.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 83a9091..5536b60 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -65,6 +65,7 @@
 
 typedef __u32		ext2_ino_t;
 typedef __u32		blk_t;
+typedef __u64		blk64_t;
 typedef __u32		dgrp_t;
 typedef __u32		ext2_off_t;
 typedef __s64		e2_blkcnt_t;