[Bug libstdc++/69881] with gcc-6 of today building gcc-4.9 fails

[bernd.edlinger at hotmail dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69881

--- Comment #11 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
(In reply to Jakub Jelinek from comment #10)
> Why should libstdc++ try to workaround a bug in gmp.h?  Just fix gmp.h...

Yes, and probably it is already fixed with gmp-6.1.0, I did not check.

I am trying to bootstrap gcc-4.9 plus the cfns.h patch from yesterday
together with a fixed gmp-4.3.2 which is just what download_prerequisites
installed.

IMHO libstdc++ is just fragile if it lets those __need_-thingies
pass through and then assumes that max_align_t must be defined.

And the free-standing cstdlib is simply not defining offsetof
when it apparently tries to.