Filter stdout for 051-thread when running on a Linux VM.

When testing on VM (regardless of the target architecture), the
underlying system is Linux not Android, and max thread priority differs
from the expected one. Filter out the offending lines from test output,
as otherwise the test passes.

Bug: 271573990
Test: run ART test 051-thread on a Linux RISC-V VM:

  lunch aosp_riscv64-userdebug

  export ART_TEST_SSH_USER=ubuntu
  export ART_TEST_SSH_HOST=localhost
  export ART_TEST_SSH_PORT=10001
  export ART_TEST_ON_VM=true

  . art/tools/buildbot-utils.sh
  art/tools/buildbot-build.sh --target

  # Create, boot and configure the VM.
  art/tools/buildbot-vm.sh create
  art/tools/buildbot-vm.sh boot
  art/tools/buildbot-vm.sh setup-ssh  # password: 'ubuntu'

  art/tools/buildbot-cleanup-device.sh
  art/tools/buildbot-setup-device.sh
  art/tools/buildbot-sync.sh

  art/test.py --target -r --no-prebuild --ndebug --64 --interpreter \
    051-thread

Change-Id: Ica690c3e7d787271ee82cc3ca19a969bb2da4250
diff --git a/test/051-thread/run.py b/test/051-thread/run.py
new file mode 100644
index 0000000..918e076
--- /dev/null
+++ b/test/051-thread/run.py
@@ -0,0 +1,26 @@
+#
+# Copyright 2023 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+import os
+
+
+def run(ctx, args):
+  ctx.default_run(args)
+  if os.environ.get("ART_TEST_ON_VM"):
+    # On Linux, max thread priority is not the same as on Android, but otherwise
+    # test results are the same. Cut the offending line to make the test pass.
+    line = "thread priority for t[12] was 5 \[expected Thread.MAX_PRIORITY\]"
+    ctx.run(fr"sed -i -E '/{line}/d' '{args.stdout_file}'")