BaseTools: Fix a bug for --pcd used in ConditionalStatement calculate

Move the GlobalData.BuildOptionPcd before FdfParser() function and add
type check for Pcd item.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/Workspace/MetaFileParser.py

@@ -1245,6 +1245,8 @@ class DscParser(MetaFileParser):
             Macros.update(self._Symbols)
         if GlobalData.BuildOptionPcd:
             for Item in GlobalData.BuildOptionPcd:
+                if type(Item) is tuple:
+                    continue
                 PcdName, TmpValue = Item.split("=")
                 TmpValue = BuildOptionValue(TmpValue, self._GuidDict)
                 Macros[PcdName.strip()] = TmpValue