This lets you run LO build tests while that LO is confined by
apparmor.

It assumes that you can have RW access to wherever LO actually needs
it in the instdir.  This obviously doesn't superseed file permissions
so you can still make the binaries read-only, etc.

Change-Id: I313459cdf115f4fda5f621b2a0c9a1da022ef525
Reviewed-on: https://gerrit.libreoffice.org/26987Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>