Enabling LTO for release binaries


I was wondering if there is a reason why we don't enable LTO for the
official binary builds? In my experience it gives a 5-10% performance
boost and reduces the size of the binaries. I understand that it
requires that release builds are built with LLD or gold with plugin on
Linux, but for macOS thin LTO is supported out of the box and on Linux
I think we build a bootstrap lld and could use that for using LTO.

Obviously late for 10.0 - but for upcoming 11 is this something we
should consider?