Fix SELinux errors caused by multi-threading

Occasionally the selinux_test program will fail because we are setting file
context based on the Process ID but not the TID.  THis change will always
use the TID to set SELinux labels.

Docker-DCO-1.1-Signed-off-by: Daniel Walsh <dwalsh@redhat.com> (github: rhatdan)
Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: crosbymichael)
Update devicemapper to pass mount flag
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Update process labels to be set at create not start
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Add cli flag to docs for selinux support
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Do not return labels when in privileged mode
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Add mountlabel to dev
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #4607 from vbatts/vbatts-static_registry

static registry support
Cleanup existing controllers when cleanup fails mid-way.

Docker-DCO-1.1-Signed-off-by: Rohit Jnagal <jnagal@google.com> (github: rjnagal)
Merge pull request #5474 from crosbymichael/use-proper-scheme

Use proper scheme with static registry
docs: DisableNetwork -> NetworkDisabled

Docker-DCO-1.1-Signed-off-by: Samuel Reis <srijs@airpost.net> (github: srijs)
Merge pull request #5476 from rjnagal/libcontainer-fixes

Cleanup cgroups on Set failures
Merge pull request #5475 from srijs/patch-1

docs: DisableNetwork -> NetworkDisabled
Update working-with-docker.md
Add a TESTDIRS variable to the test bundle to allow for the running of a
single go directory worth of tests.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)
Merge pull request #5478 from amangoel/patch-1

Update working-with-docker.md
Merge pull request #5460 from tianon/no-pull-scratch

Use "docker load" to create "scratch" in hack/make/test-integration-cli (instead of implicitly pulling it from the index)
Merge pull request #5440 from ostezer/docs-improve-code-block-rendering

Docs/CSS: Amend code block rendering.
Merge pull request #5477 from vmarmol/add-testdirs

Add a TESTDIRS variable to the test bundle to control which directories are unit tested
Close extraneous file descriptors in containers

Without this patch, containers inherit the open file descriptors of the daemon, so my "exec 42>&2" allows us to "echo >&42 some nasty error with some bad advice" directly into the daemon log. :)

Also, "hack/dind" was already doing this due to issues caused by the inheritance, so I'm removing that hack too since this patch obsoletes it by generalizing it for all containers.

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add new test-unit make rule which only runs the unit tests. Renames test
bundle to test-unit.

Docker-DCO-1.1-Signed-off-by: Victor Marmol <vmarmol@google.com> (github: vmarmol)