This patch adds the basic library functions to create and replay delta
information.  Also included is a test-delta utility to validate the
code.

diff-delta was based on LibXDiff written by Davide Libenzi
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NDavide Libenzi <davidel@xmailserver.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>