Sandbox the tracker extractor

tracker was not included by default in any Ubuntu 12.04 flavor and libseccomp is only available in backports there.

I don't intend to try to backport this change for Ubuntu 14.04 either. Ubuntu GNOME 14.04 has only a few months of support left. I don't feel it's worth the work to try to make these changes there.

I went ahead and uploaded this for yakkety as a regular SRU (it's in the unapproved queue now)

Hello Jeremy, or anyone else affected,

Accepted tracker into yakkety-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/tracker/1.10.2-0ubuntu0.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

When I looked earlier, I couldn't easily backport this to 16.04 LTS.

After a few months, I believe the tracker sandbox still causes regressions since it blocks stuff that used to be allowed. The new tracker (with sandbox) will be shipped in 17.04 and Debian stretch, but I think this update is not worth doing for 17.04 given that 17.04 is already halfway through it short life and given that we are unlikely to be able to fix all regressions it introduces.