A package recently failed building exclusively for this architecture,
therefore test it as well.

Signed-off-by: Paul Spooren <mail@aparcar.org>

By using `feeds install -d y` the CI tries to install e.g. `libcxx`
which fails, unrelated to the tested packages. Now follow the approach
of the current CircleCI implementation.

Signed-off-by: Paul Spooren <mail@aparcar.org>

The CI adds the `packages.git` repository to the `feeds.conf`, which
makes the repository redundant. Once called `packages` including the
upstream status, once `packages_ci` (previously `action`) including the
PRs changes.

This commit changes the binary artifact folder from `packages` to
`packages_ci`, as the SDK choses packages from the modified PR branch
over the `packages` branch.

Also add additional targets to test, as each target only takes a few
minutes to test: aarch64_cortex-a53, arm_cortex-a15_neon-vfpv4 and
i386_pentium4.

Signed-off-by: Paul Spooren <mail@aparcar.org>

Test all GitHub pull requests for multiple architectures and store build
logs and created packages. This is the first commit of a series of
patches to simplify the life of maintainers.

Signed-off-by: Paul Spooren <mail@aparcar.org>