libvirt.tests.virsh_memtune: Replace incompatible py 2.4 construct

The keyword 'with' is valid only on py >= 2.5. We'll have
to wait a bit before those can be freely used.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
libvirt.virsh_schedinfo_qemu_posix: Remove py 2.4 incompatible construct

With is valid only on py >= 2.5. We'll have to wait
a bit until it can be used in virt-test code.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
virttest.utils_cgroup_unittest: Make it compatible with python 2.4

This unittest relied on a new param of the tempfile.NamedTemporaryFile
class: delete. Python 2.4 doesn't have such param, which means that
named temp files will always be deleted after they are closed.

So let's use the module only to give us a file path, that will then
be manually managed.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #1289 from autotest/fix-py24-bugs

Fix py24 bugs