BaseTools: compare GUID value should not case-sensitive

build report error when the same Guid value in FDF file use lowercase,
in tools_def.txt file use uppercase.
The guid value's compare should not case-sensitive.

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

BaseTools/Source/Python/GenFds/GenFds.py

@@ -399,7 +399,7 @@ def FindExtendTool(KeyStringList, CurrentArchList, NameGuid):
     ToolOptionKey = None
     KeyList = None
     for ToolDef in ToolDefinition.items():
-        if NameGuid == ToolDef[1]:
+        if NameGuid.lower() == ToolDef[1].lower() :
             KeyList = ToolDef[0].split('_')
             Key = KeyList[0] + \
                   '_' + \