Do not stream TYPE_NEEDS_CONSTRUCTING

[Jan Hubicka]

> On Tue, 6 Nov 2018, Jan Hubicka wrote:
> 
> > Hi,
> > TYPE_NEEDS_CONSTRUCTING is one of reasons why we get duplicated complete and
> > incomplete types after my patch because the incoplete type I construct
> > may have TYPE_NEEDS_CONSTRUCTING set.
> > 
> > I think this flag is useless and can be dropped - the only use in ipa-pure-const
> > seems confused since we should drop the readonly flag on such variables.
> 
> Did you check that with an assert?

You can't assert on this easily because constructor may end up being
optimized out and the variable promoted to readonly for valid reasons.

Honza