kernel: simplify /boot/boot: 28K down to less than 4K.

kernel: simplify /boot/boot: 28K down to less than 4K.

- avoid print() format routines (saves alot of code)
- avoid useless opens of /dev/cons (already done by initcode)
- avoid useless binds of /env and /dev (already done by initcode)
- do bind of /shr in bootrc, it is not needed by us
- we'r pid 1 so kernel will print the exit message for us