if we don't support the auth return original res

make sure we return the original 401 if we don't support the auth.

Author: David Maloney

lib/rex/proto/http/client.rb

@@ -431,6 +431,7 @@ def send_auth(res, opts, t, persist)
 			end
 			return res
 		end
+		return res
 	end
 
 	def basic_auth_header(username,password)