Import macro directly rather than using #[macro_use].

`extern crate` makes it harder to keep track of dependencies, so we
prefer to import macros explicitly instead.

Bug: 261037227
Test: m keystore2_unsafe_fuzzer
Change-Id: I0ec95e9343a05c8f61c2cdca3ba601bae97c9187
diff --git a/keystore2/src/fuzzers/keystore2_unsafe_fuzzer.rs b/keystore2/src/fuzzers/keystore2_unsafe_fuzzer.rs
index 4c2419a..1a385e7 100644
--- a/keystore2/src/fuzzers/keystore2_unsafe_fuzzer.rs
+++ b/keystore2/src/fuzzers/keystore2_unsafe_fuzzer.rs
@@ -16,8 +16,6 @@
 
 #![feature(slice_internals)]
 #![no_main]
-#[macro_use]
-extern crate libfuzzer_sys;
 
 use core::slice::memchr;
 use keystore2::{legacy_blob::LegacyBlobLoader, utils::ui_opts_2_compat};
@@ -31,7 +29,7 @@
 };
 use keystore2_selinux::{check_access, getpidcon, setcon, Backend, Context, KeystoreKeyBackend};
 use keystore2_vintf::{get_aidl_instances, get_hidl_instances};
-use libfuzzer_sys::arbitrary::Arbitrary;
+use libfuzzer_sys::{arbitrary::Arbitrary, fuzz_target};
 use std::{ffi::CString, sync::Arc};
 
 // Avoid allocating too much memory and crashing the fuzzer.