timerfd: Add nsec validity check to timerfd_settime

According to the manual page, the nsec field from both it_value
and it_interval must be checked, if wrong, return EINVAL.

Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
build.mk: remove --vga from cmdline on osv.vmdk/.vdi

Now we enabled both VGA and serial, we nolonger need to add --vga cmdline for VMW/VBox.

Reviewed-by: Asias He <asias@cloudius-systems.com>
Signed-off-by: Takuya ASADA <syuu@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>