C++: Fine tune behavior of "expand macros" flag

Even if "expand funcion-like macros" is unset we still
perform the expansion in the case it's already doing
so - when it originally started from an object-like macro.

Task-number: QTCREATORBUG-7712
Change-Id: Ie2a24de227f757d195146477d48246472082d28a
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: hjk <qthjk@ovi.com>