Change conf.c to export function write_id_mapping, which will now be
called inside main function of lxc_unshare.c.

This is required because setuid syscalls only permits a new userns to
set a new uid if the uid of parameter is mapped inside the ns using
uid_map file[1]. So, just after the clone invocation, map the uid passed as
parameter into the newly created user namespace, and put the current uid
as the ID-outside-ns. After the mapping is done, setuid call succeeds.

Closes: #494

[1] https://elixir.free-electrons.com/linux/latest/source/kernel/user_namespace.c#L286Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>

tools/lxc_usernsexec: removed internal logging

tools/lxc_unfreeze: removed internal logging

tools/lxc_top: removed internal logging

tools/lxc_stop: removed internal logging

tools/lxc_start: removed internal logging

tools/lxc_snapshot: removed internal logging

tools/lxc_ls: remove internal logging

tools/lxc_monitor: removed internal logging

tools/lxc_info: removed internal logging

tools/lxc_freeze: remove internal logging

tools/lxc_execute: removed internal logging

tools/lxc_unshare: removed internal logging

tools/lxc_device: remove internal logging

tools/lxc_destroy: remove internal logging

tools/lxc_create: remove internal logging

tools/lxc_copy: remove internal logging

tools/lxc_console: remove internal logging

tools/lxc_clone: remove internal logging

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

Signed-off-by: AustinReichert <austinskyreichert@utexas.edu>

utils.h: Avoid duplicated sethostname implementation

tools/lxc_autostart: remove internal logging

tools/lxc_cgroup: remove internal logging