Add new block driver for the VDI format (only aio supported)

This is a new block driver written from scratch
to support the VDI format in QEMU.

VDI is the native format used by Innotek / SUN VirtualBox.

Latest changes:

* stripped down version
  (code for synchronous operations and experimental code removed)

* don't open VDI snapshot images (with uuid_link or uuid_parent)

* modified vdi_aio_cancel
Signed-off-by: NStefan Weil <weil@mail.berlios.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Message-Id: 

Makefile

@@ -71,7 +71,7 @@ block-obj-y = cutils.o cache-utils.o qemu-malloc.o qemu-option.o module.o
 block-obj-y += nbd.o block.o aio.o aes.o
 block-obj-$(CONFIG_AIO) += posix-aio-compat.o
 
-block-nested-y += cow.o qcow.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o
+block-nested-y += cow.o qcow.o vdi.o vmdk.o cloop.o dmg.o bochs.o vpc.o vvfat.o
 block-nested-y += qcow2.o qcow2-refcount.o qcow2-cluster.o qcow2-snapshot.o
 block-nested-y += parallels.o nbd.o
 block-nested-$(CONFIG_WIN32) += raw-win32.o

qemu-img.texi

@@ -48,6 +48,8 @@ Old QEMU image format. Left for compatibility.
 User Mode Linux Copy On Write image format. Used to be the only growable
 image format in QEMU. It is supported only for compatibility with
 previous versions. It does not work on win32.
+@item vdi
+VirtualBox 1.1 compatible image format.
 @item vmdk
 VMware 3 and 4 compatible image format.
 @item cloop