_assert is a kernel procedure, entered via system call to make the core
dump in privileged mode.
Running exit() from this context is not OK as it runs the registered
exit functions and flushes streams, which must not be done
from privileged mode as it is a security hole.
Thus, implement assert() into user space (again) and remove the exit()
call from the kernel procedure.
Instantiate the correct address environment when reading the process's
argument vector. Otherwise doing this will crash the system every time,
causing a recursive assert loop.
Also try to do a bit of sanity checking before attempting to read the
process's memory, it might be in a bad state in which case this will
fail anyway.
