Re-adding pvspinlock for performance

Should be supported by now
Update Whonix-Custom-Workstation_qemu.xml
Update Whonix-Gateway_kvm.xml
Update Whonix-Gateway_qemu.xml
Update Whonix-Workstation_kvm.xml
Update Whonix-Workstation_qemu.xml
Merge pull request #374 from HulaHoopWhonix/patch-97

Re-adding pvspinlock for performance
Merge pull request #375 from HulaHoopWhonix/patch-98

Update Whonix-Custom-Workstation_qemu.xml
Merge pull request #376 from HulaHoopWhonix/patch-99

Update Whonix-Gateway_kvm.xml
Merge pull request #377 from HulaHoopWhonix/patch-100

Update Whonix-Gateway_qemu.xml
Merge pull request #378 from HulaHoopWhonix/patch-101

Update Whonix-Workstation_kvm.xml
Merge pull request #379 from HulaHoopWhonix/patch-102

Update Whonix-Workstation_qemu.xml
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Merge remote-tracking branch 'origin/master'