test: Fix use of allowed_failures in pathological_tests.py

The test needs to check if the test description is a valid key in the
allowed_failures dictionary instead of attempting to fetch from the
dictionary as most of the descriptions are not present in the
dictionary leading to a missing key error at runtime.

Signed-off-by: Keith Packard <keithp@keithp.com>

Author: keith-packard

test/pathological_tests.py

@@ -146,12 +146,12 @@ def run_test(inp, regex):
             p.terminate()
             p.join()
             print('[TIMED OUT]')
-            if allowed_failures[description]:
+            if description in allowed_failures:
                 ignored += 1
             else:
                 errored += 1
         elif p.exitcode != 0:
-            if allowed_failures[description]:
+            if description in allowed_failures:
                 ignored += 1
             else:
                 errored += 1