srm-client: Report srmPutDone failure

srmcp currently ignores failures to finalize an upload with srmPutDone.
This patch fixes that problem.

Target: trunk
Request: 2.10
Require-notes: yes
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7405/