BaseTool: Fixed Pcd issues.

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>

BaseTools/Source/Python/Workspace/BuildClassObject.py

@@ -114,6 +114,7 @@ class StructurePcd(PcdClassObject):
         if validateranges is None: validateranges=[]
         if validlists is None: validlists=[]
         if expressions is None : expressions=[]
+        if Packages is None : Packages = []
         super(StructurePcd, self).__init__(Name, Guid, Type, DatumType, Value, Token, MaxDatumSize, SkuInfoList, IsOverrided, GuidValue, validateranges, validlists, expressions)
         self.StructuredPcdIncludeFile = [] if StructuredPcdIncludeFile is None else StructuredPcdIncludeFile
         self.PackageDecs = Packages