t0008: 4 tests fail with ksh88

t0008: 4 tests fail with ksh88

In t0008, we have

	cat <<-EOF
	...
	a/b/.gitignore:8:!on*	"a/b/one\"three"
	...
	EOF

and expect that the backslash-dq is passed through literally.

ksh88 eats the backslash and produces a wrong expect file to
compare the actual output with.

Using \\" works this around without breaking other POSIX shells
(which collapse backslash-backslash to a single backslash), and
ksh88 does so, too.

It makes it easier to read, too, because the reason why we are
writing backslash there is *not* because we think dq is special and
want to quote it (if that were the case we would have two more
backslashes on that line).  It is simply because we want a single
literal backslash there.  Since backslash is treated specially in
unquoted here-document, explicitly doubling it to quote it expresses
our intent better than relying on the character that immediately
comes after it (i.e. '"') not being a special character.

Signed-off-by: Armin Kunaschik <megabreit@googlemail.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>