autoconf: allow Release to contain hyphen

To avoid clashing with tags and releases, we'll use "zfs-macOS".

Meta: 1
Name: zfs-macOS

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Jorgen Lundman <lundman@lundman.net>
Closes #12437