zdtm.sh: set correct path for dump files (v3)

Don't use an uninitialized variable to create a path pattern.

v2: fix the comment
v3: don't use readlink -m, which isn't supported by busybox

Cc: Christopher Covington <cov@codeaurora.org>
Reported-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Reviewed-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm/cwd01: avoid resolving an abs path

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Reported-by: Mr Jenkins
Fixes: 7dbd38dbc939 ("zdtm: set additional groups along with uids and gids")
Cc: Ruslan Kuprieiev <kupruser@gmail.com>
Signed-off-by: Andrew Vagin <avagin@openvz.org>
Acked-by: Ruslan Kuprieiev <kupruser@gmail.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>