fix code completion after multiple occurrences of public,private or protected

this was especially noteable after Q_OBJECT public: since the
Q_OBJECT macro ends with a private:

the reason is that our poor-mans tokenizer got confused by the
colon in PARENT_ACCESS_STRINGS, returning it directly even though
if the colon is preceded by public, private or protected we
don't actually have the single-colon case.

so now we check the full list and then double-check
that we actually have a access string