ubox: update to git head

	- use dynamically sized buffer, fixes label extraction on vfat partitions with huge cluster size
	- strip trailing spaces from vfat labels, aligns behaviour with "blkid"

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37529 3c298f89-4303-0410-b956-a3cf2f4a3e73