In the most cases, file descriptor is not need in this function.
It's need in the case of creating a regular file only. So we can
use chown() instead of fchown(), and operate with a path directly.

The patch moves copying content of a regular file to new function
mkreg_ghost(). This will be used in next patches. Also, parameter
gf will be used.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>