Revert "Implement ar-file parsing in python (#8681)"

[sbc100]

This reverts commit 1d198e4.

Apparently this cause a failure on the mac builder:
https://ci.chromium.org/p/emscripten-releases/builders/ci/mac/b8911649373078606944

cache:INFO:  - ok
Traceback (most recent call last):
  File "/b/s/w/ir/k/install/emscripten/emcc.py", line 3391, in <module>
    sys.exit(run(sys.argv))
  File "/b/s/w/ir/k/install/emscripten/emcc.py", line 1894, in run
    final = shared.Building.link(linker_inputs, DEFAULT_FINAL, force_archive_contents=force_archive_contents, just_calculate=just_calculate)
  File "/b/s/w/ir/k/install/emscripten/tools/shared.py", line 1940, in link
    Building.read_link_inputs([x for x in files if not x.startswith('-')])
  File "/b/s/w/ir/k/install/emscripten/tools/shared.py", line 1721, in read_link_inputs
    object_names_in_archives = pool.map(extract_archive_contents, archive_names)
  File "/b/s/w/ir/cipd_bin_packages/lib/python2.7/multiprocessing/pool.py", line 253, in map
    return self.map_async(func, iterable, chunksize).get()
  File "/b/s/w/ir/cipd_bin_packages/lib/python2.7/multiprocessing/pool.py", line 572, in get
    raise self._value
IOError: [Errno 2] No such file or directory: u'/b/s/w/ir/tmp/t/emscripten_temp_oIE5H7_archive_contents/#1/12'

[kripken]

Another option may be to disable the test on mac for now. That may be safer if you are worried about merge conflicts when trying to land this later.

[kripken]

Oh nm, if seems like it fails in the build steps on the bots, so it might not be a single test to disable.

[sbc100]

I'm generally happy to revert early and revert often.