REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2798 The services in CpuLib usually generate exceptions in a unit test host application. Provide a Null instance that can be safely used. This Null instance can also be used as a template for implementing new instances of CpuLib. Cc: Liming Gao <liming.gao@intel.com> Cc: Sean Brogan <sean.brogan@microsoft.com> Cc: Bret Barkelew <Bret.Barkelew@microsoft.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com> Reviewed-by: Liming Gao <liming.gao@intel.com> Reviewed-by: Sean Brogan <sean.brogan@microsoft.com> Reviewed-by: Liming Gao <liming.gao@intel.com>