pppossh: use exec with pty option to eliminate a level of bufferbloat

While at it, also do the following fixes

 - Drop the URL pointing to the old github repo
 - Fix detection of default set of private keys

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

net/pppossh/Makefile

@@ -8,7 +8,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=pppossh
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 PKG_MAINTAINER:=Yousong Zhou <yszhou4tech@gmail.com>
 PKG_LICENSE:=GPLv2
 
@@ -18,7 +18,6 @@ define Package/pppossh
   SECTION:=net
   CATEGORY:=Network
   TITLE:=PPPoSSH (Point-to-Point Protocol over SSH)
-  URL:=https://github.com/yousong/waller
   DEPENDS:=+ppp +resolveip @(PACKAGE_dropbear||PACKAGE_openssh-client)
 endef
 

net/pppossh/files/pppossh.sh

@@ -46,7 +46,7 @@ proto_pppossh_setup() {
 	[ -n "$sshuser" ] || errmsg="${errmsg}Missing sshuser option\n"
 
 	json_get_values identity identity
-	[ -z "$identity" ] && identity="'$home/.ssh/id_rsa' '$home/.ssh/id_dsa'"
+	[ -z "$identity" ] && identity="$home/.ssh/id_rsa $home/.ssh/id_dsa"
 	for fn in $identity; do
 		[ -f "$fn" ] && opts="$opts -i $fn"
 	done
@@ -60,7 +60,7 @@ proto_pppossh_setup() {
 	opts="$opts ${port:+-p $port}"
 	opts="$opts ${ssh_options}"
 	opts="$opts $sshuser@$server"
-	pty="env 'HOME=$home' "$SSH" $opts pppd nodetach notty noauth"
+	pty="exec env 'HOME=$home' $SSH $opts pppd nodetach notty noauth"
 
 	ppp_generic_setup "$config" noauth pty "$pty" "$ipaddr:$peeraddr"
 }