jool: version bump (fixes #3657)

Latest upstream changes explicitly include `net/ip6_checksum.h`.
Fixes issue #3657.

Signed-off-by: Dan Luedtke <mail@danrl.com>

net/jool/Makefile

@@ -7,7 +7,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=jool
-PKG_VERSION:=3.5.2
+PKG_VERSION:=2016.12.17
 PKG_RELEASE:=1
 
 PKG_LICENSE:=GPL-3.0
@@ -15,7 +15,7 @@ PKG_LICENSE_FILES:=COPYING
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://github.com/NICMx/Jool.git
-PKG_SOURCE_VERSION:=ec32f7181d6b12eadcafbe39b8bf4d7d48230232
+PKG_SOURCE_VERSION:=66a791c90751d7941b08c142babe1deec73d0996
 PKG_SOURCE_SUBDIR:=$(PKG_NAME)-$(PKG_SOURCE_VERSION)
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_SOURCE_VERSION).tar.xz