C++ PATCH for c++/88979 - further P0634 fix for constructors

[Jason Merrill]

On 3/13/19 1:25 PM, Marek Polacek wrote:
> This PR points out that our P0634 implementation misses constructor parameters
> and still requires 'typename'.  I'm not 100% sure if the standard really says
> we should also handle constructors.  Does a constructor have a function type?

Not that we can ask about, but a constructor declaration is a function 
declaration.

> But I guess it makes sense, so this patch handles it.  To handle a constructor
> in a class, we need to pass flags to cp_parser_constructor_declarator_p.  To
> handle an out-of-line constructor, use constructor_name_p.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

OK.

Jason