criu/files: Fix wait_fds_event() for 64 bit platforms

The htole64() function returns a 64 bit value. This is stored in
a 32 bit integer in wait_fds_event() which results in 0 for big-endian
64 bit platforms. The fuxtex() system call also requires 32 bit values.

Fix this and use htole32() also for 64 bit platforms.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>