Not sure. Seems wrong to say that OS X will never need to accept a user-defined argument to `--with-ld-opt`. For mac, we explicitly install pcre-dist but that's not the only thing that could be missing (or in a strange place) in someone's environment. We get a warning about `/usr/local/lib` not being found, but other than that it works.

But saying that, there's less variability in OS X setups so maybe users won't have to configure this...