x86: fix PROCESS_STACK_GET

Signed-off-by: Levente Kurusa <levex@linux.com>
sched: add destroy procedures

Signed-off-by: Levente Kurusa <levex@linux.com>
sched: clean up a few comments

Signed-off-by: Levente Kurusa <levex@linux.com>
tty: prepare for tty support

Signed-off-by: Levente Kurusa <levex@linux.com>