soccr: rectify Alpine build

Made a symlink to CRIU's generated config.h, played with
moving some code to soccr.h header.
Changed types from u32 to uint32_t, otherwise we should
include CRIU's "int.h" in soccr, but I'm lazy to add that.

Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>