[PATCH] NUL terminate diff-tree header lines under -z.

[PATCH] NUL terminate diff-tree header lines under -z.

Thomas Glanzmann noticed that diff-tree -z HEAD piped to
diff-helper -z did not work.  Since diff-helper -z expects NUL
terminated lines, we should generate such.

The output side of the diff-helper should always be using '\n'
termination; earlier it used the same line_termination used for
the input side, which was a mistake.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>