Custom makepkg.conf
I've just made a change to the default makepkg.conf
to restore it to more sane defaults. See packages/core/pacman#7 (comment 27826)
I'll take a look later and see about an MR if I figure it out. Either way, it should be fairly simple to set a custom MAKEFLAGS
value.
EDIT: I won't push the changes until this is resolved.