Revert "Handle non-Apple packaged GCC versions"

[DavidSpickett]

Reverts #34 due to an error running the test suite on our Linux bots. https://lab.llvm.org/buildbot/#/builders/17/builds/10167 for example.

Traceback (most recent call last):
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/bin/lnt", line 33, in <module>
    sys.exit(load_entry_point('LNT', 'console_scripts', 'lnt')())
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/lib/python3.10/site-packages/click-6.7-py3.10.egg/click/core.py", line 722, in __call__
    return self.main(*args, **kwargs)
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/lib/python3.10/site-packages/click-6.7-py3.10.egg/click/core.py", line 697, in main
    rv = self.invoke(ctx)
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/lib/python3.10/site-packages/click-6.7-py3.10.egg/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/lib/python3.10/site-packages/click-6.7-py3.10.egg/click/core.py", line 1066, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/lib/python3.10/site-packages/click-6.7-py3.10.egg/click/core.py", line 895, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/sandbox/lib/python3.10/site-packages/click-6.7-py3.10.egg/click/core.py", line 535, in invoke
    return callback(*args, **kwargs)
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/lnt/lnt/tests/test_suite.py", line 1189, in cli_action
    results = test_suite.run_test(test_suite.opts)
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/lnt/lnt/tests/test_suite.py", line 310, in run_test
    cc_info = self._get_cc_info(cmake_vars)
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/lnt/lnt/tests/test_suite.py", line 714, in _get_cc_info
    return lnt.testing.util.compilers.get_cc_info(
  File "/home/tcwg-buildbot/worker/clang-aarch64-sve-vla/test/lnt/lnt/testing/util/compilers.py", line 79, in get_cc_info
    m = re.match(r'(.*) version ([^ ]*) (?:[0-9]+ )?+(\([^(]*\))(.*)',
  File "/usr/lib/python3.10/re.py", line 190, in match
    return _compile(pattern, flags).match(string)
  File "/usr/lib/python3.10/re.py", line 303, in _compile
    p = sre_compile.compile(pattern, flags)
  File "/usr/lib/python3.10/sre_compile.py", line 788, in compile
    p = sre_parse.parse(p, flags)
  File "/usr/lib/python3.10/sre_parse.py", line 955, in parse
    p = _parse_sub(source, state, flags & SRE_FLAG_VERBOSE, 0)
  File "/usr/lib/python3.10/sre_parse.py", line 444, in _parse_sub
    itemsappend(_parse(source, state, verbose, nested + 1,
  File "/usr/lib/python3.10/sre_parse.py", line 672, in _parse
    raise source.error("multiple repeat",
re.error: multiple repeat at position 33