Import local_state only once

This fixes a "error[E0659]: `PSTATE` is ambiguous (glob import vs glob
import in the same module)" error I ran into.
The old build scripts used to copy "local_state.rs" into the src
directory for every tool. I see that all the tools in the examples
directory have stopped doing that. And sure enough, once I updated my
tool to do the same, it fixed this particular error. But we
should still get rid of the duplicate import.

trampoline/ffi.rs

@@ -10,7 +10,6 @@
 use core::ffi::c_void;
 use crate::consts;
 use crate::captured_syscall;
-use crate::local_state::*;
 
 use tools_helper::local_state::*;
 use syscalls::*;