BaseTools: Fix the bug for VOID* pcd max size from component section

When the Pcd defined in components section, its value's size is larger
than the value's size in [pcd] section, it cause build error, because
original code use the size get in [pcd] section as max size.

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/BuildClassObject.py

@@ -1,7 +1,7 @@
 ## @file
 # This file is used to define each component of the build database
 #
-# Copyright (c) 2007 - 2017, Intel Corporation. All rights reserved.<BR>
+# Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
 # This program and the accompanying materials
 # are licensed and made available under the terms and conditions of the BSD License
 # which accompanies this distribution.  The full text of the license may be found at
@@ -55,6 +55,7 @@ class PcdClassObject(object):
         self.DefaultValue = Value
         self.TokenValue = Token
         self.MaxDatumSize = MaxDatumSize
+        self.MaxSizeUserSet = None
         self.SkuInfoList = SkuInfoList
         self.Phase = "DXE"
         self.Pending = False