I cannot build libsass on Mac OSX 10.7 (Lion)

I get this error while trying to build libsass via pip on Mac OSX 10.7.

```
cc1: error: -Werror=unused-command-line-argument-hard-error-in-future: No option -Wunused-command-line-argument-hard-error-in-future
```

It looks like its a flag only supported by newer versions of GCC, and OSX 10.7 is stuck with GCC 1.2 via XCode and friends. Do you know of some way around this?
