tools/libs/evtchn: decouple more from mini-os

tools/libs/evtchn: decouple more from mini-os

Mini-OS and libevtchn are using implementation details of each other.
Change that by letting libevtchn use the new alloc_file_type() and
get_file_from_fd() function and the generic dev pointer of struct file
from Mini-OS.

By using private struct declarations Mini-OS will be able to drop the
libevtchn specific definitions of struct evtchn_port_info and
evtchn_port_list in future. While at it use bool for "pending" and
"bound".

Switch to use xce as function parameter instead of fd where possible.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>