Fix regressions introduced with --build option

The changes to reinstate the --build option introduced two
regressions:

- Running sosreport with no otions generates a backtrace due to
  a non-existant _build member in the SoSOptions object

- Running sosreport without --build leaves the temporary archive
  directory in places with the sos_logs directory containing
  sos.log and ui.log due to changes in the order of log shutdown
  and archive creation.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>