ls-files and read-tree need core.filemode

ls-files and read-tree need core.filemode

ls-files.c and read-tree.c miss the default configuration, in
particular the filemode=false part.  The recent +x bit flip made me
notice that, because git-merge refused to merge anything saying that
git-pull.sh is not up to date.

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