Evangelos Foutras authored Feb 10, 2022 and Allan McRae committed Mar 06, 2022

We want to use -flto=auto in Arch Linux to speed up building, but we
can't hardcode it in buildenv/lto.sh because other downstreams might
have clang < 13.0.0 which did not recognize -flto=auto as equivalent
to -flto=full.

Introducing an LTOFLAGS variable to makepkg.conf seems the way to go.

Signed-off-by: Allan McRae <allan@archlinux.org>