Linux Sandbox: reorganize

Linux Sandbox: reorganize

This CL creates a new integrations_tests/ directory, and splits
bpf_dsl_more_unittests.cc into two files.

Moreover, this creates a new system_headers/ directory and moves
current system headers there.

This helps organizing our dependencies better.

BUG=449357
TBR=mseaborn

Committed: https://crrev.com/aedcc3ee8d28d0354ad3106ef8deaa369506ab3c
Cr-Commit-Position: refs/heads/master@{#315922}

[jln (very slow on Chromium), 2015-02-12 00:59:52]

jln@chromium.org changed reviewers:
+ mdempsky@chromium.org

[jln (very slow on Chromium), 2015-02-12 01:01:51]

Matthew: could you please take a look?

This is pretty much entirely mechanical. If you want to, you could take a look
at the names in integration_tests/.

[mdempsky, 2015-02-12 02:46:03]

LGTM

I suspect we can move seccomp-bpf/linux_seccomp.h into system_headers too (in a
separate CL).

[jln (very slow on Chromium), 2015-02-12 03:00:57]

The CQ bit was checked by jln@chromium.org

[commit-bot: I haz the power, 2015-02-12 03:01:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/921563002/40001

[commit-bot: I haz the power, 2015-02-12 03:07:16]

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

[commit-bot: I haz the power, 2015-02-12 03:07:17]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[jln (very slow on Chromium), 2015-02-12 03:13:26]

mseaborn: TBR for components/nacl/loader/DEPS

[jln (very slow on Chromium), 2015-02-12 03:13:31]

The CQ bit was checked by jln@chromium.org

[commit-bot: I haz the power, 2015-02-12 03:14:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/921563002/40001

[commit-bot: I haz the power, 2015-02-12 03:18:18]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-12 03:20:14]

Patchset 3 (id:??) landed as
https://crrev.com/aedcc3ee8d28d0354ad3106ef8deaa369506ab3c
Cr-Commit-Position: refs/heads/master@{#315922}