This patch adds a new qemu-io tool that links against the block layer and
image formats and allow to exercise them without needing a guest image.
It is inspired by the xfs_io tool which does the same for plain file I/O.
In fact the libxcmd library which is the backend of xfs_io is reused by this
tool in a limited fashing (cmd.[ch] files).

This version tests out most of the plain block I/O commands with the
most notable absent commands beeing snapshot handling and real aio.

This tool is the basis of the I/O path test suite I'm working on right now.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6990 c046a42c-6fe2-441c-8c8c-71466251a162