Plug diff leaks.

It is a bit embarrassing that it took this long for a fix since the
problem was first reported on Aug 13th.

    Message-ID: <87y876gl1r.wl@mail2.atmark-techno.com>
    From: Yasushi SHOJI <yashi@atmark-techno.com>
    Newsgroups: gmane.comp.version-control.git
    Subject: [patch] possible memory leak in diff.c::diff_free_filepair()
    Date: Sat, 13 Aug 2005 19:58:56 +0900

This time I used valgrind to make sure that it does not overeagerly
discard memory that is still being used.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff-tree.c

@@ -370,6 +370,7 @@ static int diff_tree_commit(const unsigned char *commit, const char *name)
 		}
 		offset += 48;
 	}
+	free(buf);
 	return 0;
 }