[source] openvpn: add "extra-certs" option

[LEDE Commits]

yousong pushed a commit to source.git, branch master:
https://git.lede-project.org/ce53c0e718b4451cf58680df8299a0647e1c48d8

commit ce53c0e718b4451cf58680df8299a0647e1c48d8
Author: Sven Roederer <devel-sven at geroedel.de>
AuthorDate: Tue Sep 5 18:27:02 2017 +0200

    openvpn: add "extra-certs" option
    
    This option is used to specify a file containing PEM certs, to complete the
    local certificate chain. Which is quite usefull for "split-CA" setups.
    
    Signed-off-by: Sven Roederer <devel-sven at geroedel.de>
    Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
---
 package/network/services/openvpn/Makefile              | 2 +-
 package/network/services/openvpn/files/openvpn.options | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/package/network/services/openvpn/Makefile b/package/network/services/openvpn/Makefile
index 537a1bf..a1aa196 100644
--- a/package/network/services/openvpn/Makefile
+++ b/package/network/services/openvpn/Makefile
@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 PKG_NAME:=openvpn
 
 PKG_VERSION:=2.4.3
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE_URL:=\
 	https://build.openvpn.net/downloads/releases/ \
diff --git a/package/network/services/openvpn/files/openvpn.options b/package/network/services/openvpn/files/openvpn.options
index 022f530..a6a3ded 100644
--- a/package/network/services/openvpn/files/openvpn.options
+++ b/package/network/services/openvpn/files/openvpn.options
@@ -30,6 +30,7 @@ ecdh_curve
 echo
 engine
 explicit_exit_notify
+extra_certs
 fragment
 group
 hand_window