app-emulation/qemu: add qemu to improve streamOptimized vmdk support for VMware OVF

Fixes https://github.com/coreos/bugs/issues/176.

I added the patch to improve streamOptimized vmdk support.
If we don't use it, we can't deploy OVF to ESXi or vCenter.

For more details:
http://lists.gnu.org/archive/html/qemu-devel/2014-07/msg01151.html