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>