qemu.virttest.qemu_vm: Update the way used to create vhostfd

Follow the way used to add tapfds when creating vhostfd.
This can help us try to reuse vhostfd instead of getting a new
vhostfd every time.
Release vhostfd.
Support multi queue

Signed-off-by: Feng Yang <fyang@redhat.com>
shared.cfg: adding Win2012R2 guest-os cfg

Note:
1) after it GA, we need to update the iso path.
2) the origin Win2012 has name named Win2012.x86_64.r1

Signed-off-by: Xiaoqing Wei <xwei@redhat.com>
shared.cfg: adding Win8.1 guest-os cfg

Note:
1) after it GA, we need to update the iso path.
2) the origin Win8 has named, Win8.i386.0 Win8.x86_64.0

Signed-off-by: Xiaoqing Wei <xwei@redhat.com>