bug#17806: 24.4.50; Branch emacs-24 fails to beuild on Debian

[Dmitry Antipov]

On 06/21/2014 01:06 AM, Stefan Monnier wrote:

> If it tends to break (and since IIUC it's new in 24.4), we could also
> remove it from 24.4.

Well, this is considered experimental and known for its controversial results
(for example, see http://www.phoronix.com/scan.php?page=news_item&px=MTI5ODE).
I didn't make representative benchmarks; as for the crashes, code compiled with
'-O2 -flto' looks more stable than '-O3 -march=native -mtune=native' (YMMV).

After all, --enable-link-time-optimization is not enabled by default (and never
should be), users aren't enforced to enable it - so I don't see a problem here;
INSTALL may warn about potentially unstable results of using this option.

Dmitry