registry: make certain headers optional

For a pull-only, static registry, there only a couple of headers that
need to be optional (that are presently required.
* X-Docker-Registry-Version
* X-Docker-Size
* X-Docker-Endpoints

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
registry: Info collection

roll version and standalone information into the _ping. And to support
Headers they are checked after the JSON is loaded (if there is anything
to load). To stay backwards compatible, if the _ping contents are not
able to unmarshal to RegistryInfo, do not stop, but continue with the
same behavior.

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)
Engine: optional Logging field to disable custom logging in engine.

* The default behavior is preserved
* This disables the use of the `TEST` environment variable in engine.

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)
Update check-config.sh with more kernel configs and more reliable cgroup hierarchy/subsystem check

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Added reactive-docker to list of remote API clients

Docker-DCO-1.1-Signed-off-by: H. Rapp <webmaster@3kolor.com> (github: almoehi)
Use LLVM Clang explicitly on FreeBSD

Docker-DCO-1.1-Signed-off-by: Kato Kazuyoshi <kato.kazuyoshi@gmail.com> (github: kzys)
Unlike GNU find, FreeBSD's find needs a path before an expression

Docker-DCO-1.1-Signed-off-by: Kato Kazuyoshi <kato.kazuyoshi@gmail.com> (github: kzys)
Support FreeBSD on pkg/system/utimes_*.go

Implement system.LUtimesNano and system.UtimesNano. The latter might be
removed in future because it's basically same as os.Chtimes. That's why
the test is mainly focusing LUtimesNano.

Docker-DCO-1.1-Signed-off-by: Kato Kazuyoshi <kato.kazuyoshi@gmail.com> (github: kzys)
refactor build job to know only configFile

Docker-DCO-1.1-Signed-off-by: Victor Vieux <victor.vieux@docker.com> (github: vieux)
Setup cgroups for all subsystems

Fixes #5117
Fixes #5118
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Join cpuacct, freezer, perf_event, and blkio groups
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Join memory and cpu cgroup in systemd too

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: crosbymichael)
Enable construction of TruncIndex from id array.

Fixes #5166

Current graph.restore is essentially O(n^2 log n) due to how
suffixarray creation works.

Rather than create/append/create new this supports creation from a seed
array of ids.

Functional testing shows this eliminates the hang on Creating image
graph reported on list.

Docker-DCO-1.1-Signed-off-by: Paul Nasrat <pnasrat@gmail.com> (github: pnasrat)
Add the test to reproduce the issue even in "make test"

Docker-DCO-1.1-Signed-off-by: Kato Kazuyoshi <kato.kazuyoshi@gmail.com> (github: kzys)
Fix utils.FollowSymlinkInScope's infinite loop bug

fs_test.go doesn't finish if Docker's code is placed under a directory
which has symlinks between / and the directory.
For example, the below doesn't finish before the change.

  /home -> usr/home
  FollowSymlinkInScope("/home/bob/foo/bar", "/home/bob/foo")

Docker-DCO-1.1-Signed-off-by: Kato Kazuyoshi <kato.kazuyoshi@gmail.com> (github: kzys)
Docs: add some example log lines that indicate a lack of memory when running the test suite

Docker-DCO-1.1-Signed-off-by: Jean-Baptiste Barth <jeanbaptiste.barth@gmail.com> (github: jbbarth)
Docs: improve installation/ubuntulinux memory and swap accounting section

Docker-DCO-1.1-Signed-off-by: Jean-Baptiste Barth <jeanbaptiste.barth@gmail.com> (github: jbbarth)
Merge pull request #5178 from jbbarth/docs-improve-ubuntulinux-accounting-section

Docs: improve installation/ubuntulinux memory and swap accounting section
Merge pull request #5177 from jbbarth/docs-add-common-errors-for-test-suite

Docs: add some example log lines that indicate a lack of memory when running the test suite
cli integ: don't fetch busybox if it exists

Don't make calls to the registry if the image exists already.

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)