No need to include syscall.h, use 1024 as the max # of entries (the

No need to include syscall.h, use 1024 as the max # of entries (the
max that systrace(4) allows).

Only need to use SYSTR_POLICY_ASSIGN once

Change check_syscall() -> find_handler() and have it return the
handler instead of just running it.  We need this since handler now
have two parts: one part that generates and answer and another that
gets called after the answer is accepted (to do logging).

Add some missing check_exec for emul execv