Linux: Add a script to generate a Precise dpkg admin dir for use with official builds on Trusty.

Linux: Add a script to generate a Precise dpkg admin dir for use with official builds on Trusty.

With the output dpkg admin dir, dpkg-shlibdeps can generate the right package dependencies.

Copied from thestig@'s CL
https://codereview.chromium.org/786543004/

BUG=564904

[Tom (Use chromium acct), 2016-10-04 23:45:37]

Description was changed from

==========
Linux: Add a script to generate a Precise dpkg admin dir for use with official
builds on Trusty.

With the output dpkg admin dir, dpkg-shlibdeps can generate the right package
dependencies.
==========

to

==========
Linux: Add a script to generate a Precise dpkg admin dir for use with official
builds on Trusty.

With the output dpkg admin dir, dpkg-shlibdeps can generate the right package
dependencies.
==========

[Tom (Use chromium acct), 2016-10-04 23:45:37]

thomasanderson@google.com changed reviewers:
+ phajdan.jr@chromium.org, thestig@chromium.org

[Tom (Use chromium acct), 2016-10-04 23:46:03]

Description was changed from

==========
Linux: Add a script to generate a Precise dpkg admin dir for use with official
builds on Trusty.

With the output dpkg admin dir, dpkg-shlibdeps can generate the right package
dependencies.
==========

to

==========
Linux: Add a script to generate a Precise dpkg admin dir for use with official
builds on Trusty.

With the output dpkg admin dir, dpkg-shlibdeps can generate the right package
dependencies.

Copied from thestig@'s CL
https://codereview.chromium.org/786543004/

BUG=564904
==========

[Tom (Use chromium acct), 2016-10-05 01:54:58]

Hopefully we'll be able to use sbc@'s CL instead
https://codereview.chromium.org/2391183002/, but we can use this if for some
reason the sysroot change doesn't work

[Tom (Use chromium acct), 2016-10-05 01:55:18]

The CQ bit was checked by thomasanderson@google.com to run a CQ dry run

[commit-bot: I haz the power, 2016-10-05 01:55:33]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-05 02:10:42]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-10-05 02:10:43]

Dry run: This issue passed the CQ dry run.

[Sam Clegg, 2016-10-05 02:23:59]

On 2016/10/05 01:54:58, Tom Anderson wrote:
> Hopefully we'll be able to use sbc@'s CL instead
> https://codereview.chromium.org/2391183002/, but we can use this if for some
> reason the sysroot change doesn't work

I'll keep working on 2391183002.  In the mean time I think it would be
cleaner/easier to simply add expected_deps_trusty in order to unblock 564904.  
What we have today is basically expected_deps_precise, its just not called that,
so it wouldn't be making things worse IMHO.