Hi Henri,
I thought I would experiment with the --lto option for the build script, unfortunately, building with the flag is unsuccessful on my rig. I'm currently running Fedora 27 which includes using gcc 7.2.1 and cmake 3.10.1. Omitting the --lto flag produces a successful, executable build, as I have done many times (though I also include the --tune flag). I realize use of the new flag is experimental, as you noted in the changelog, so success might not be possible without significant investigation. I attached the capture of the build stdout/err which shows segfaults that might be to blame (though not much else of use). Abrt reports that:
triggered a (the first?) crash. I have included a file with some of the output from that as well.
Unfortunately, I'm a bit out of my depth. If there is a simple suggestion or two, I would pursue it/them. No expectations here though. I am content to build my usual way but when you introduce something new, I almost always want to 'tinker'.
Cheers!