What I've been doing is keeping a list of offending packages in a list
in mk.conf, and then checking whether PKGBASE/PKGNAME (like
devel/cpuflags does) is in that list.  If it is, I set
MAKE_JOBS_SAFE=no (you can do _MAKE_JOBS=, MAKE_JOBS=1 also if you
want).

There are also a fair number of packages which work with user-destdir
that aren't marked as such.

I've been thinking about attempting to devise a wrapper that, upon a
build failure of a package, marks it down and then tries again without
MAKE_JOBS.  Haven't had the time, though.

Regards,

--Blair