Add support for executing an init binary as PID 1 in a container to
forward signals and reap processes. When the `--init` flag is set for
podman-create or podman-run, the init binary is bind-mounted to
`/dev/init` in the container and "/dev/init --" is prepended to the
container's command.
The default base path of the container-init binary is `/usr/libexec/podman`
while the default binary is catatonit [1]. This default can be changed
permanently via the `init_path` field in the `libpod.conf` configuration
file (which is recommended for packaging) or temporarily via the
`--init-path` flag of podman-create and podman-run.
[1] https://github.com/openSUSE/catatonitFixes: #1670
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>
