schedinfo_qemu_posix: Add cases change schedinfo by xml

This patch changed cputune info in domain xml and then restart the
domain to validate it with cgroup observation. This is a regression
test base on a known bug.

Also the emulatorpin test is changed to fit new vm_xml.

Signed-off-by: Hao Liu <hliu@redhat.com>
Merge pull request #81 from Hao-Liu/fix_schedinfo

schedinfo_qemu_posix: Add cases change schedinfo by xml