Main changes are as the following

 - Allow specifying port in server option, e.g. example.com:1702 (fixes
   github issue #1960 "xl2tpd port change bug").
 - Fixes NULL dereference on connection timeout
 - Update 100-makefile_opt_flags.patch

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>