[Bug other/59893] Use LTO for libgcc.a, libstdc++.a, etc

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59893

--- Comment #5 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to Marc Glisse from comment #0)
> It may be as easy as adding the flags to C(XX)FLAGS_FOR_TARGET

With a trivial fix for PR 43538, this works. However, we then hit PR 59472.
Also, if instead of gold 1.11 (which works fine) I use GNU ld 2.24, I get
warnings:
/usr/bin/ld: error in /tmp/cc5iP5Yf.ltrans2.ltrans.o(.eh_frame); no
.eh_frame_hdr table will be created.
because of crtend.o.

The path is long... At least, I tried the result, and it does help for PR 59048
and does allow removing operator delete(0).