[post] prune extra names already in standard Mac set
[post] prune extra names already in standard Mac set

This should fix https://github.com/fonttools/fonttools/issues/1119

Running `ftxvalidator -T tt0004c_#1.ttf` no longer produces this error
message, but passes with 'NA'

```
Fatal
    post: The name data overflow the table bounds.
        kATSFontTestSeverityFatalError
```

fonttools/fonttools,googlefonts/fonttools