Add functions that have been added to MdePkg/UefiLib. * GetVariable2() * GetEfiGlobalVariable2 Cc: Sean Brogan <sean.brogan@microsoft.com> Cc: Jiewen Yao <jiewen.yao@intel.com> Cc: Liming Gao <liming.gao@intel.com> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com> Reviewed-by: Star Zeng <star.zeng@intel.com> Reviewed-by: Bret Barkelew <Bret.Barkelew@microsoft.com>