Darwin: The symbol `_9' does not fit here.

c2hs (or language-c) does not seem to be able to parse the value `10_9`

```
c2hs: C header contains errors:

/nix/store/pz99r8hkn8ym8vpn45hfj441py9r82qz-apple-framework-CoreFoundation/Library/Frameworks/CoreFoundation.framework/Headers/CFBase.h:665: (column 117) [ERROR] >>> Syntax error !
The symbol `_9' does not fit here.
```

The line in CFBase.hs is this:

```
CFTypeRef CFAutorelease(CFTypeRef CF_RELEASES_ARGUMENT arg) CF_AVAILABLE(10_9, 7_0);
```

I definition for `CF_AVAILABLE` seems to be this:

```
#define CF_AVAILABLE(_mac, _ios) __attribute__((availability(macosx,introduced=_mac)))
```

**c2hs version**: `0.28.6`