fix gost error when do not type http2 port (haoel#119)

Author: codepiano

scripts/install.ubuntu.18.04.sh

@@ -177,7 +177,7 @@ install_shadowsocks(){
 
     BIND_IP=0.0.0.0
 
-    if [[ -z "${PORT// }" ]] || ! [[ "${PORT}" =~ ^[0-9]+$ ]] || ! [ "$PORT" -ge 1 ] && [  "$PORT" -le 655535 ]; then
+    if [[ -z "${PORT// }" ]] || ! [[ "${PORT}" =~ ^[0-9]+$ ]] || ! ([ "$PORT" -ge 1 ] && [  "$PORT" -le 65535 ]); then
         echo -e "${COLOR_ERROR}非法端口,使用默认端口 1984 !${COLOR_NONE}"
         PORT=1984
     fi