Implement per-test timeout guard

Timeout value can be specified by test in suite.conf:

config:
  suite:
    <suite_name>:
      <test_name>:
        timeout: 2 # 2 seconds timeout

Change-Id: I522f51f77f8be64ebfdb5d5e07ba92baf82d7706
diff --git a/selftest/suite_test/suite_test.py b/selftest/suite_test/suite_test.py
index 260b9c4..9708037 100755
--- a/selftest/suite_test/suite_test.py
+++ b/selftest/suite_test/suite_test.py
@@ -102,7 +102,7 @@
 s = suite.SuiteRun(trial, 'test_suite', s_def, [sc])
 s.reserve_resources()
 print(repr(s.reserved_resources))
-results = s.run_tests('test_suite_params.py')
+results = s.run_tests(['test_suite_params.py', 'test_timeout.py'])
 print(report.suite_to_text(s))
 
 print('- test with template overlay')