BaseTools:Updata the output encoding of the Popen function

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=2015

Not all output works in utf-8, so change the encoding to
the default

This patch is going to fix that issue.

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/Workspace/DscBuildData.py

@@ -1735,7 +1735,7 @@ class DscBuildData(PlatformBuildClassObject):
         except:
             EdkLogger.error('Build', COMMAND_FAILURE, 'Can not execute command: %s' % Command)
         Result = Process.communicate()
-        return Process.returncode, Result[0].decode(encoding='utf-8', errors='ignore'), Result[1].decode(encoding='utf-8', errors='ignore')
+        return Process.returncode, Result[0].decode(), Result[1].decode()
 
     @staticmethod
     def IntToCString(Value, ValueSize):