Fix most common parsing failures when @ is present in the docblock but not for an annotation

Replaces https://github.com/doctrine/common/pull/195  - in the most common path this just adds one `$input[$pos] !== ' ' && $input[$pos] !== '*'` check which I think is worth fixing this WTF-inducing-bug, really not much compared to the whole annotation parsing, and it's cached anyway right?