Fix permission bits on sources checked out with an overtight umask

Fix permission bits on sources checked out with an overtight umask

Two patches 9907721 (templates/Makefile: don't depend on local umask
setting, 2008-02-28) and 96cda0b (templates/Makefile: install is
unnecessary, just use mkdir -p, 2008-08-21) tried to prevent an overtight
umask the builder/installer might have from screwing over the installation
procedure, but we forgot there was another source of trouble.  If the
person who checked out the source tree had an overtight umask, it will
leak out to the built products, which is propagated to the installation
destination.

Signed-off-by: Junio C Hamano <gitster@pobox.com>