1. Check variable offset when merging Hii Pcds 2. Fixed the issue of Hii value inherit with default store. 3. Error handling for incorrect structure pcd declare. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Bob Feng <bob.c.feng@intel.com> Cc: Liming Gao <liming.gao@intel.com> Reviewed-by: Liming Gao <liming.gao@intel.com>