libnftnl: bump to latest git

Signed-off-by: Steven Barth <steven@midlink.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43706 3c298f89-4303-0410-b956-a3cf2f4a3e73
nftables: bump to latest git, fix mini-gmp patches

Signed-off-by: Steven Barth <steven@midlink.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43707 3c298f89-4303-0410-b956-a3cf2f4a3e73