tests/rpm: always run ./autogen.sh to create missing files

In some occasions 'install-sh' seems to be missing in the 'make dist'
tarball when ./autogen.sh has not been run (skipped when 'configure'
exists). With this changes, 'autogen.sh' is always run so that missing
files should get added to the tarball.

Also write the logs from mock to a known location, and copy them to the
'/var/log/' directory that Jenkins archives after a regression test
failure. This makes it easier to find build issues that mock detects.

Cherry picked from commit 79de5b63775f1ab8e2e498fd51b55509a30cd896:
> Change-Id: I8d0cf1afef61ebab0137aa0d20521e75a35ddbdd
> BUG: 1038391
> Signed-off-by: Niels de Vos <ndevos@redhat.com>
> Reviewed-on: http://review.gluster.org/7786
> Tested-by: Gluster Build System <jenkins@build.gluster.com>
> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
> Reviewed-by: Anand Avati <avati@redhat.com>

Change-Id: I8d0cf1afef61ebab0137aa0d20521e75a35ddbdd
BUG: 1089054
Signed-off-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/7850
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>