Fix setuid on OSX when you make install

Fix GNS3/gns3-gui#2167

Author: julien-duponchelle

Makefile

@@ -83,8 +83,8 @@ all	: $(NAME)
 ifeq ($(shell uname), Darwin)
 install : $(NAME)
 	cp $(NAME) $(BINDIR)
-	chmod 4755 $(BINDIR)/$(NAME)
-	chown root $(BINDIR)/$(NAME)
+	chown root:admin $(BINDIR)/$(NAME)
+	chmod 4750 $(BINDIR)/$(NAME)
 else
 install : $(NAME)
 	chmod +x $(NAME)