Attempt to support clang (osx/freebsd)

[asottile]

Resolves #7

CC @nils-werner

I assume there's a better way of detecting the compiler but this seems to work?

[nils-werner]

I see you are trying to infer the Go compiler from the setuptools compiler. I don't know if they are always the same and if things would even work if they weren't. However I would still argue that specifically asking Go for its compiler would be the more consistent solution.

The following asks go (go env CXX) for its compiler instead of asking the setuptools one.

def _guess_compiler():
    # Attempt to guess the compiler
    out = subprocess.check_output(('go', 'env', 'CXX'))
    for possible in ('clang', 'gcc'):  # pragma: no cover (platform specific)
        if possible.encode('US-ASCII') in out:
            return possible
    else:  # pragma: no cover (platform specific)
        # Patches welcome!
        return 'gcc'

def _get_ldflags():
    cc = _guess_compiler()
    return {
        'clang': '-Wl,-undefined,dynamic_lookup',
        'gcc': '-Wl,--unresolved-symbols=ignore-all',
    }[cc]

What do you think?

[asottile]

I actually went with a solution based on a question I asked on SO: http://stackoverflow.com/questions/42195333/detect-compiler-and-use-compiler-specific-flags-when-invoking

Also I think I want CC (CXX is the c++ compiler)