Fix cap drop issues with lxc

This uses "," instead of spaces so that the flags are parsed correctly
and also does not do a strings.Split on an empty string because
strings.Split will return a slice with one element, and empty string
causing parsing to fail when it validates that the cap exists.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Use : to split caps in sysinit flags
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@docker.com> (github: crosbymichael)
Skip whole dir dockerignoring with warning

Fixes #7093
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
integration-cli: add more tests for BuildAddTar

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
integration-cli/TestBuildAddTar: generate context from test

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
integration-cli/TestBuildAddTar: embed Dockerfile

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
pkg/units: Using 'case' instead of trickled ifs

Seems the perfect case for 'case' ;).

Docker-DCO-1.1-Signed-off-by: Francisco Carriedo <fcarriedo@gmail.com> (github: fcarriedo)
pkg/units: Standardized supported sizes

May make sense that both `FromHumanSize()` and `RAMInBytes()` support
the same units. Added 'PB' to the RAMInBytes regex.

Also updated tests.

Note: int64 is overflowed on quantities >= EB

Docker-DCO-1.1-Signed-off-by: Francisco Carriedo <fcarriedo@gmail.com> (github: fcarriedo)
pkg/units: Refactor regexp.Compile to init()

No need to recompile a fixed regular expression each time the function
executes. Abstracting it to the `init()` method.

Docker-DCO-1.1-Signed-off-by: Francisco Carriedo <fcarriedo@gmail.com> (github: fcarriedo)
pkg/units: Compacted var declaration and initialization

No need to have two lines. The type is even explicit when type casting
to `float64(size)`

Docker-DCO-1.1-Signed-off-by: Francisco Carriedo <fcarriedo@gmail.com> (github: fcarriedo)
pkg/units: Moved 'units' out of function

No need to initialize every time the function executes since it works as
a catalog.

Docker-DCO-1.1-Signed-off-by: Francisco Carriedo <fcarriedo@gmail.com> (github: fcarriedo)
pkg/units: Refactored common code to single func

Both functions perform the same logic and they just vary on the base
multiplication units. We can refactor the common code into a single
place.

Docker-DCO-1.1-Signed-off-by: Francisco Carriedo <fcarriedo@gmail.com> (github: fcarriedo)
Test on building from GIT url

Also I added fake git server to utils
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
pkg/units: Updated `Compile()` to `MustCompile()`

We were doing exactly what `regexp.MustCompile()` already does.

Docker-DCO-1.1-Signed-off-by: fcarriedo <fcarriedo@gmail.com> (github: fcarriedo)
pkg/units: including suggestions and enhancements

Docker-DCO-1.1-Signed-off-by: fcarriedo <fcarriedo@gmail.com> (github: fcarriedo)
compile unit tests in parallel with GNU parallel

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
benign whitespace change

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Add a bunch more tweaks to the parallel test compilation

- put all the precompiled test binaries in $DEST so they show up in bundles and can be re-run individually afterwards
- support cases where parallel is not installed (when using dyntest-unit, for example, this is much more common, since it's designed to be run outside the Dockerfile)
- use "mktemp -d" instead of "/tmp" directly for our temporary parallel HOME
- update the default PARALLEL_JOBS to be the value of "nproc" instead of 0, since "0 means as many as possible" (see https://www.gnu.org/software/parallel/man.html#jobs_n)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
remove temporary line in Dockerfile that prevented cache miss

Docker-DCO-1.1-Signed-off-by: Tibor Vass <teabee89@gmail.com> (github: tiborvass)
Fix precompiled unit tests needing their "testdata" contents

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)