Fix import_path circular dependency by splitting it out.

Use import thread_pool instead from, from is evil.

Fix poweroff.out path for ./trace-boot.

build-crosstool-ng

@@ -61,7 +61,7 @@ Build crosstool-NG with Newlib for bare metal compilation
                 'build', LF,
                 'CT_JOBS={}'.format(str(self.env['nproc'])), LF,
             ],
-            out_file=os.path.join(build_dir, 'lkmc.log'),
+            out_file=os.path.join(build_dir, self.env['repo_short_id'] + '.log'),
             delete_env=['LD_LIBRARY_PATH'],
             extra_paths=[self.env['ccache_dir']],
         )