[v3] use -Wl,-z,relro if possible

[Paolo Carlini]

Paolo Carlini wrote:

>Wrt testresults, I'm building --disable-bootstrap and I'm wondering
>whether it's a miscompilation of sort: right now I'm in the middle of a
>default build, complete bootstrap.
>
No progress. I can confirm that on my x86-linux machine (stock
glibc-2.3.6, by the way) binutils-2.16.1 doesn't play well with
--gc-sections.

FWIW, I'm now using binutils-2.16.91.0.5 and with it, everything seems
fine. No idea why...

Paolo.