ubox: update to latest git head

make sure log buffer size is not bigger than the ubus message size

Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@39365 3c298f89-4303-0410-b956-a3cf2f4a3e73