Split warn.py into multiple files

* Split warning patterns into *_warn_patterns.py
* Split project list into android_project_list.py
* Split out the Severity class, to be changed later
* Split core of warn.py into warn_common.py and
  leave only platform dependent code in warn.py.
  This allows the core logic be used with different
  parallel processing libraries.
* Old warn.py just calls -m warn.warn.

Test: path_to_build/tools/warn.py build.log
Test: warn.py --url=http://cs/android --separator='?l=' build.log > warnings.html
Change-Id: I6734e4472a21018cd5ce06d549f6dbca24f4de54
diff --git a/tools/warn/warn.py b/tools/warn/warn.py
new file mode 100755
index 0000000..252f073
--- /dev/null
+++ b/tools/warn/warn.py
@@ -0,0 +1,37 @@
+#!/usr/bin/python
+#
+# Copyright (C) 2019 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.
+
+"""Simple wrapper to run warn_common with Python standard Pool."""
+
+import multiprocessing
+
+# pylint:disable=relative-beyond-top-level
+from .warn_common import common_main
+
+
+# This parallel_process could be changed depending on platform
+# and availability of multi-process library functions.
+def parallel_process(num_cpu, classify_warnings, groups):
+  pool = multiprocessing.Pool(num_cpu)
+  return pool.map(classify_warnings, groups)
+
+
+def main():
+  common_main(parallel_process)
+
+
+if __name__ == '__main__':
+  main()