qemu: Resolve issue with GetScheduler APIs for non running domain

As a consequence of the cgroup layout changes from commit '632f78ca', the
qemuDomainGetSchedulerParameters[Flags]()' and qemuGetSchedulerType() APIs
failed to return data for a non running domain.  This can be seen through
a 'virsh schedinfo <domain>' command which returns:

Scheduler      : Unknown
error: Requested operation is not valid: cgroup CPU controller is not mounted

Prior to that change a non running domain would return:

Scheduler      : posix
cpu_shares     : 0
vcpu_period    : 0
vcpu_quota     : 0
emulator_period: 0
emulator_quota : 0

This patch will restore the capability to return configuration only data
for a non running domain regardless of whether cgroups are available.
(cherry picked from commit b23754534193fb7a1e31306d94ae5f09759a0aa4)
lxc: Resolve issue with GetScheduler APIs for non running domain

As a consequence of the cgroup layout changes from commit 'cfed9ad4', the
lxcDomainGetSchedulerParameters[Flags]()' and lxcGetSchedulerType() APIs
failed to return data for a non running domain.  This can be seen through
a 'virsh schedinfo <domain>' command which returns:

Scheduler      : Unknown
error: Requested operation is not valid: cgroup CPU controller is not mounted

Prior to that change a non running domain would return:

Scheduler      : posix
cpu_shares     : 0
vcpu_period    : 0
vcpu_quota     : 0
emulator_period: 0
emulator_quota : 0

This patch will restore the capability to return configuration only data
for a non running domain regardless of whether cgroups are available.
(cherry picked from commit 38ada092d1ad5f27a24e511173308d568b6b085f)