zstream: force-install zstreamdump link

Accidentally introduced by commit dd00925e8d.

Force-install the zstreamdump link, this is a supported configuration
and the install should not fail if it needs to overwrite an existing
file.

Also cd to work around some funny platforms as noted in AC_PROG_LN_S doc

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12143