Initialize adlist variable in getrouteaddr(), so an illegal address

doesn't cause a traceback.

Lib/rfc822.py

@@ -450,6 +450,7 @@ class AddrlistClass:
         expectroute = 0
         self.pos = self.pos + 1
         self.gotonext()
+        adlist = None
         while self.pos < len(self.field):
             if expectroute:
                 self.getdomain()