[Android] Add --dirmd-path to getowners.py, not functional

In builders, the path to dirmd needs to be passed as parameter. Add it
preemptively so that when the recipe CL lands, this step doesn't fail
due to the unexpected parameter.

The parameter will be used when DIR_METADATA is parsed in getowners.py:
https://chromium-review.googlesource.com/c/chromium/src/+/2645158

Bug: 1135347
Change-Id: Iee8ae9c653a8f41690ba357323f15294a2e91dad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2645062
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846362}

tools/android/modularization/owners/getowners.py

@@ -42,6 +42,11 @@ def main():
       '--limit-to-dir',
       help='Limit to a single directory. Used to restrict a smaller scope for '
       'debugging.')
+  # TODO(crbug.com/1135347): --dirmd-dir is currently unused, but will be used
+  # to parse DIR_METADATA files.
+  arg_parser.add_argument(
+      '--dirmd-path',
+      help="Path to dirmd. If not specified, assume it's in PATH.")
   arguments = arg_parser.parse_args()
 
   start_time = time.time()