open /dev/null for ptyfd in hyper_setup_exec_tty() when seq=0
open /dev/null for ptyfd in hyper_setup_exec_tty() when seq=0

Signed-off-by: Lai Jiangshan <b337eedf453972390e4695e362aeea2634ef4e0c@gmail.com>

gnawux/hyperstart,bergwolf/hyperstart,gnawux/hyperstart,laijs/hyperstart,bergwolf/hyperstart,gao-feng/hyperstart,MarioCarrilloA/hyperstart,hyperhq/hyperstart,gnawux/hyperstart,laijs/hyperstart,MarioCarrilloA/hyperstart,MarioCarrilloA/hyperstart,hyperhq/hyperstart,gao-feng/hyperstart