...where it appears to be necessary, as the subprocess.Popen in
uitest/libreoffice/connection.py apparently doesn't manage to make the spawned
soffice process send stdout/-err output to the python process's stdout/-err (as
works fine e.g. on Linux).  (Only using that hack on Windows has the advantage
that on other platforms output from the python and the soffice process will be
properly interspersed.  On Windows, at least sal/log.hxx messages from the
soffice process are captured that way, while its stdout/-err output is still
lost.)

Also dump the soffice.out.log content in case of failure.  (Note that, despite
the file's name, it contains any sal/log.hxx messages from both the python and
the soffice process.)

Change-Id: Ic99a62b1abbe2fbbf98128a35203e2fd05335266
Reviewed-on: https://gerrit.libreoffice.org/50620Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>