pool: Preserve HSM option ordering

Although the script should not care about the order, it might. Also,
it is nicer to see the options in the order you put them rather than
how they got hashed.

Target: trunk
Request: 2.11
Request: 2.10
Request: 2.9
Require-notes: yes
Require-book: no
Acked-by: Christian Bernardt <christian.bernardt@desy.de>
Patch: https://rb.dcache.org/r/7621/
(cherry picked from commit 1bb519f0a6be84bbbace8157d9e5f585ffe473f3)
Merge pull request #1206 from gbehrmann/fix/2.10/rb7621

pool: Preserve HSM option ordering