tools.check_patch: Allow to set AUTOTEST_PATH

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Merge pull request #1432 from ldoktor/framework3

tools.check_patch: Allow to set AUTOTEST_PATH
virttest.libvirt_xml: Add sysinfo xml handler

Add sysinfo_xml module to handle sysinfo xml operation.

Signed-off-by: Wayne Sun <gsun@redhat.com>