BaseTools:change some incorrect parameter defaults

BZ:https://bugzilla.tianocore.org/show_bug.cgi?id=1858

for Dict={},There are pitfalls in the way this default parameter is set
and Dict is not used in functions, other functions have these two cases,
I will change some incorrect parameter defaults

This patch is going to fix this issue

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

BaseTools/Source/Python/AutoGen/BuildEngine.py

@@ -176,7 +176,9 @@ class FileBuildRule:
         CommandString = "\n\t".join(self.CommandList)
         return "%s : %s\n\t%s" % (DestString, SourceString, CommandString)
 
-    def Instantiate(self, Macros={}):
+    def Instantiate(self, Macros = None):
+        if Macros is None:
+            Macros = {}
         NewRuleObject = copy.copy(self)
         NewRuleObject.BuildTargets = {}
         NewRuleObject.DestFileList = []