baremetal: allow arbitrary exit status with the magic string

test-baremetal: fix missing setting x0 return value

Examples were just returning on ret without setting x0, which led to
failures... those were not noticed because of how broken the testing system
was ;-)

test-baremetal

@@ -4,6 +4,8 @@ import os
 import sys
 
 import common
+import path_properties
+from thread_pool import ThreadPool
 
 class Main(common.TestCliFunction):
     def __init__(self):
@@ -26,6 +28,7 @@ If given, run only the given tests. Otherwise, run all tests.
 
     def timed_main(self):
         run_args = self.get_common_args()
+        rootdir_abs_len = len(self.env['root_dir'])
         with ThreadPool(
             self.run_test,
             nthreads=self.env['nproc'],
@@ -49,7 +52,7 @@ If given, run only the given tests. Otherwise, run all tests.
                                     error = thread_pool.submit({
                                         'expected_exit_status': my_path_properties['exit_status'],
                                         'run_args': cur_run_args,
-                                        'run_obj':  self.import_path_main('run'),
+                                        'run_obj': self.import_path_main('run'),
                                         'test_id': path_relative_root,
                                     })
                                     if error is not None: